Why is `&lt;form enctype=multipart/form-data&gt;` required when uploading a file to a web-server?

Why is form enctype=multipart/form-data required when uploading a file?

I&#39;ve recently been playing with the Javascript Fetch API. As far as I understand, by default all redirects are handled transparently and in the end I get a response from the last call in the redirect chain.

However, I could invoke fetch with {redirect: &#39;manual&#39;}, in which case it would return an opaqueredirect response with no usable information. From https://fetch.spec.whatwg.org/#concept-filtered-response-opaque-redirect

&gt; An opaque-redirect filtered response
is a filtered response whose type is &quot;opaqueredirect&quot;, status is 0, status message is the empty byte sequence, header list is empty, body is null, and trailer is empty.

https://fetch.spec.whatwg.org/#http-fetch says that a response gets to be opaqueredirect if redirect is set to &#39;manual&#39;:

&gt; Switch on request’s redirect mode:&lt;br/&gt;
&gt; ...&lt;br/&gt;
&gt; - manual&lt;br/&gt;
&gt; &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;Set response to an opaque-redirect filtered response whose internal response is actualResponse. 

The specification also says:
&gt; In other words, an opaque filtered response and an opaque-redirect filtered response are nearly indistinguishable from a network error.

Given all this, why would one set redirect to manual when using the Fetch API? To me it seems pretty useless. Are there use cases where this would be useful?

Fetch API - What&#39;s the use of redirect: manual

I was experimenting with how `/` is interpreted when around different keywords and operators, and found that the following syntax is perfectly legal:

&lt;!-- begin snippet: js hide: false console: true babel: false --&gt;

&lt;!-- language: lang-js --&gt;

    // awaiting something that isn&#39;t a Promise is fine, it&#39;s just strange to do:
    const foo = await /barbaz/
    myFn()

&lt;!-- end snippet --&gt;

Error:
&gt;Uncaught ReferenceError: await is not defined

It looks like it tries to parse the `await` as a *variable name*..? I was expecting

&gt;await is only valid in async function

or maybe something like

&gt;Unexpected token await

To my horror, you can even assign things to it:

&lt;!-- begin snippet: js hide: false console: true babel: false --&gt;

&lt;!-- language: lang-js --&gt;

    const await = &#39;Wait, this actually works?&#39;;
    console.log(await);

&lt;!-- end snippet --&gt;

Shouldn&#39;t something so obviously wrong cause a syntax error, as it does with `let`, `finally`, `break`, etc? Why is this allowed, and what the heck is going on in the first snippet?

Why are await and async valid variable names?

Example:
Is the following code valid against the [JSON Spec][1]?

    {
        precision: &quot;zip&quot;
    }

Or should I always use the following syntax? (And if so, why?)

    {
        &quot;precision&quot;: &quot;zip&quot;
    }

I haven&#39;t really found something about this in the JSON specifications. Although they use quotes around their keys in their examples.

  [1]: https://www.rfc-editor.org/rfc/rfc4627

Do the JSON keys have to be surrounded by quotes?

As the subject asks; do UNIX timestamps change in each timezone?

**For example,** if I sent a request to another email the other side of the world saying, **&quot;Send out an email when the time is 1397484936&quot;**, would the other server&#39;s timestamp be 12 hours behind my own?

Do UNIX timestamps change across timezones?

Web applications that want to force a resource to be _downloaded_ rather than directly _rendered_ in a Web browser issue a `Content-Disposition` header in the HTTP response of the form:

&lt;code&gt;Content-Disposition: attachment; filename=&lt;em&gt;FILENAME&lt;/em&gt;&lt;/code&gt;

The `filename` parameter can be used to suggest a name for the file into which the resource is downloaded by the browser. [RFC 2183][1] (Content-Disposition), however, states in [section 2.3][2] (The Filename Parameter) that the file name can only use US-ASCII characters:

&gt; Current [RFC 2045] grammar restricts
&gt; parameter values (and hence
&gt; Content-Disposition filenames) to
&gt; US-ASCII.  We recognize the great
&gt; desirability of allowing arbitrary
&gt; character sets in filenames, but it is
&gt; beyond the scope of this document to
&gt; define the necessary mechanisms.

There is empirical evidence, nevertheless, that most popular Web browsers today seem to permit non-US-ASCII characters yet (for the lack of a standard) disagree on the encoding scheme and character set specification of the file name. Question is then, what are the various schemes and encodings employed by the popular browsers if the file name “na&#239;vefile” (without quotes and where the third letter is U+00EF) needed to be encoded into the Content-Disposition header?

For the purpose of this question, _popular browsers_ being:

  - Google Chrome 
  - Safari
  - Internet Explorer or Edge
  - Firefox 
  - Opera

  [1]: https://www.rfc-editor.org/rfc/rfc2183
  [2]: https://www.rfc-editor.org/rfc/rfc2183#section-2.3


How to encode the filename parameter of Content-Disposition header in HTTP?

&gt; **Possible Duplicate:**  
&gt; [What&amp;#39;s the use/meaning of the @ character in variable names in C#?](https://stackoverflow.com/questions/91817/whats-the-use-meaning-of-the-character-in-variable-names-in-c)  

&lt;!-- End of automatically inserted text --&gt;

I understand that the @ symbol can be used before a string literal to change how the compiler parses the string.  But what does it mean when a variable name is prefixed with the @ symbol?

What does the @ symbol before a variable name mean in C#?

As far as I know, `private` is the default *everywhere* in C# (meaning that if I don&#39;t write `public`, `protected`, `internal`, etc. it will be `private` by default). (Please correct me if I am wrong.)

So, what&#39;s the reason to write that keyword, or why does it even exist for members?

For example, when an event handler is auto-generated it looks like this:

    private void RatTrap_MouseEnter(object sender, CheeseEventArgs e)
    {
        
    }

But why does it even write private if that&#39;s implied and default? Just so that novice developers (who don&#39;t know it&#39;s the C# default) know that it&#39;s private? Or is there a difference for the compiler?

Moreover, is there a case where writing &quot;private&quot; (alone) *will* change the accessibility of the member?


Any reason to write the &quot;private&quot; keyword in C#?

Background (question further down)
===

I&#39;ve been Googling this back and forth reading RFCs and SO questions trying to crack this, but I still don&#39;t got jack.

So I guess we just vote for the &quot;best&quot; answer and that&#39;s it, or?

Basically it boils down to this.

&gt; 3.4. Query Component
&gt; 
&gt; The query component is a string of information to be interpreted by the resource.
&gt; 
&gt; `query         = *uric`
&gt; 
&gt; Within a query component, the characters &quot;;&quot;, &quot;/&quot;, &quot;?&quot;, &quot;:&quot;, &quot;@&quot;, &quot;&amp;&quot;, &quot;=&quot;, &quot;+&quot;, &quot;,&quot;, and &quot;$&quot; are reserved.

The first thing that boggles me is that *uric is defined like this

&gt; `uric          = reserved | unreserved | escaped`
&gt;
&gt; `reserved      = &quot;;&quot; | &quot;/&quot; | &quot;?&quot; | &quot;:&quot; | &quot;@&quot; | &quot;&amp;&quot; | &quot;=&quot; | &quot;+&quot; | &quot;$&quot; | &quot;,&quot;`

This is however somewhat clarified by paragraphs such as

&gt; The &quot;reserved&quot; syntax class above refers to those characters that are allowed within a URI, but which may not be allowed within a particular component of the generic URI syntax; they are used as delimiters of the components described in Section 3.
&gt;
&gt; Characters in the &quot;reserved&quot; set are not reserved in all contexts. The set of characters actually reserved within any given URI component is defined by that component. In general, a character is reserved if the semantics of the URI changes if the character is replaced with its escaped US-ASCII encoding.

This last excerpt feels somewhat backwards, but it clearly states that the reserved character set depends on context. Yet 3.4 states that all the reserved characters are reserved within a query component, however, the only things that would change the semantics here is escaping the question mark (?) as URIs do not define the concept of a query string.

At this point I&#39;ve given up on the RFCs entirely but found RFC 1738 particularly interesting.

&gt; An HTTP URL takes the form:
&gt;
&gt; `http://&lt;host&gt;:&lt;port&gt;/&lt;path&gt;?&lt;searchpart&gt;`
&gt;
&gt;  Within the &amp;lt;path&amp;gt; and &amp;lt;searchpart&amp;gt; components, &quot;/&quot;, &quot;;&quot;, &quot;?&quot; are reserved. The &quot;/&quot; character may be used within HTTP to designate a hierarchical structure.

I interpret this at least with regards to HTTP URLs that RFC 1738 supersedes RFC 2396. Because the URI query has no notion of a query string also the interpretation of reserved doesn&#39;t really let allow me to define query strings as I&#39;m used to doing by now.

Question
===

This all started when I wanted to pass a list of numbers together with the request of another resource. I didn&#39;t think much of it, and just passed it as a comma separated values. To my surprise though the comma was escaped. The query `page.html?q=1,2,3` encoded turned into `page.html?q=1%2C2%2C3` it works, but it&#39;s ugly and didn&#39;t expect it. That&#39;s when I started going through RFCs.

My first question is simply, is encoding commas really necessary?

My answer, according to RFC 2396: yes, according to RFC 1738: no

Later I found related posts regarding the passing of lists between requests. Where the csv approach was poised as bad. This showed up instead, (haven&#39;t seen this before).

    page.html?q=1;q=2;q=3

My second question, is this a valid URL?

My answer, according to RFC 2396: no, according to RFC 1738: no (; is reserved)

I don&#39;t have any issues with passing csv as long as it&#39;s numbers, but yes you do run into the risk of having to encode and decode values back and forth if the comma suddenly is needed for something else. Anyway I tried the semi-colon query string thing with ASP.NET and the result was not what I expected.

    Default.aspx?a=1;a=2&amp;b=1&amp;a=3

    Request.QueryString[&quot;a&quot;] = &quot;1;a=2,3&quot;
    Request.QueryString[&quot;b&quot;] = &quot;1&quot;

I fail to see how this greatly differs from a csv approach as when I ask for &quot;a&quot; I get a string with commas in it. ASP.NET certainly is not a reference implementation but it hasn&#39;t let me down yet.

But most importantly -- my third question -- where is specification for this? and what would you do or for that matter not do?

What&#39;s valid and what&#39;s not in a URI query?

I have a enum `SOME_ENUM`: 

    public enum SOME_ENUM {
      EN_ONE,
      EN_TWO,
      EN_THREE;
    }

Will `SOME_ENUM.values()` always return the enums in the order of enum declarations:
`EN_ONE, EN_TWO, EN_THREE`? Is it a rule or it is not guaranteed to be not changed in the next JDK releases? 

enum.values() - is an order of returned enums deterministic

It appears that when you type in a number in Java, the compiler automatically reads it as an integer, which is why when you type in (long) `6000000000` (not in integer&#39;s range) it will complain that `6000000000` is not an integer.  To correct this, I had to specify `6000000000L`.  I just learned about this specification.

Are there other number specifications like for short, byte, float, double?  It seems like these would be good to have because (I assume) if you could specify the number you&#39;re typing in is a short then java wouldn&#39;t have to cast it - that is an assumption, correct me if I&#39;m wrong.  I would normally search this question myself, but I don&#39;t know what this kind of number specification is even called.

Java&#39;s L number (long) specification

(Not to be confused with [Xunit][1], a popular .Net unit testing library.)

Today in a fit of boredom I started inspecting Gmails DOM (yes, I was very bored).

Everything looked pretty straightforward until I noticed an interesting specification on the widths of certain elements. The illustrious Googlites had specified a number of table cols using the rare &#39;ex&#39; unit.

    width: 22ex;

At first I was stumped (&quot;what&#39;s an &#39;ex&#39;?&quot;), then it came back to me: I seem to remember something from years ago when first I was learning about CSS. [From the CSS3 spec](http://www.w3.org/TR/css3-values/#ex-unit):

&gt; [The **ex unit** is] equal to the used x-height of the [first available font](http://www.w3.org/TR/css3-fonts/#first-available-font). The x-height is so called because it is often equal to the height of the lowercase &quot;x&quot;. However, an ‘ex’ is defined even for fonts that do not contain an &quot;x&quot;.

Well and good. But I&#39;ve never actually seen it used before (much less used it myself). I use ems quite commonly, and appreciate their value, but why the &quot;ex&quot;? It seems much less standard a measurement than the em, and far less useful.

One of the few pages I found discussing this topic is Stephen Poley&#39;s [http://www.xs4all.nl/~sbpoley/webmatters/emex.html][2]. Stephen makes good points, however, his discussion seems inconclusive to me.

So my question is: **What value does the &#39;ex&#39; unit lend to web design?**

(This question could be tagged subjective, but I&#39;ll leave that decision to more experienced SO&#39;ers than myself.)


  [1]: http://www.codeplex.com/xunit
  [2]: http://www.xs4all.nl/~sbpoley/webmatters/emex.html

What is the value of the css &#39;ex&#39; unit?

In HTML attribute **name=value** pairs, what are the characters allowed for the &#39;name&#39; portion? ..... Looking at some [common attributes][1] it appears that only letters (a-z and A-Z) are used, but what other chars could be allowed as well?...  maybe digits (0-9), hyphens (-), and periods (.) ... is there any spec for this?


  [1]: http://www.w3.org/TR/REC-html40/index/attributes.html

What characters are allowed in an HTML attribute name?

I want to code an application that can read and decode a pdf document; now where I&#39;m supposed to get the specs for this fileformat ? The PDF format is standardized from the ISO group but it&#39;s not clear to me where is the most reliable source for getting this kind of informations.

what is a good source to start with this file format ?

PDF specifications for coders: Adobe or ISO?

Given the following function call in `C`:

    fooFunc( barFunc(), bazFunc() );

The order of execution of `barFunc` and `BazFunc` is not specified, so `barFunc()` may be called before `bazFunc()` or `bazFunc()` before `barFunc()` in `C`. 

Does `Java` specify an order of execution of function argument expressions or like `C` is that unspecified? 

Order of execution of parameters guarantees in Java?

I read recently (I can&#39;t recall where, or I&#39;d return to that source) that the misspelling of HTTP header field name Referer in the specification was intentional.  Is that accurate?  If so, why?

Was the misspelling of the HTTP field name Referer intentional?

This is a typescript interface:

    interface A {
        l: { x: string; y:number }
    }

But this (similar thing) produces an error:

    interface A {
        l: { x: string, y:number }
    }
    
    // =&gt; Error: &#39;;&#39; expected.


On p.37 of the spec:
http://www.typescriptlang.org/Content/TypeScript%20Language%20Specification.pdf

I see that indeed it is specified that a `;` should appear there, but coming from JavaScript the semicolon in the middle of the object-literal-ish thing looks wrong.

Was this decision made to avoid ambiguity in the parser, or for some other reason?

Why is the separator in a TypeScript TypeMemberList semicolon as opposed to comma?

I get it on some level, but I have yet to see an example that didn&#39;t bring up more questions than answers.

http://rhnh.net/2011/01/31/yaml-tutorial

    # Set.new([1,2]).to_yaml
    --- !ruby/object:Set 
    hash: 
      1: true
      2: true


I get that we&#39;re declaring a Set tag.  I don&#39;t get what the subsequent hash mapping has to do with it.  Are we declaring a schema?  Can someone show me an example with multiple tag declarations?


I&#39;ve read through the spec: http://yaml.org/spec/1.2/spec.html#id2761292

    %TAG ! tag:clarkevans.com,2002:

Is this declaring a schema?  Is there something else a parser has to do in order to successfully parse the file?  A schema file of some type?

http://www.yaml.org/refcard.html

    Tag property: # Usually unspecified.
        none    : Unspecified tag (automatically resolved by application).
        &#39;!&#39;     : Non-specific tag (by default, &quot;!!map&quot;/&quot;!!seq&quot;/&quot;!!str&quot;).
        &#39;!foo&#39;  : Primary (by convention, means a local &quot;!foo&quot; tag).
        &#39;!!foo&#39; : Secondary (by convention, means &quot;tag:yaml.org,2002:foo&quot;).
        &#39;!h!foo&#39;: Requires &quot;%TAG !h! &lt;prefix&gt;&quot; (and then means &quot;&lt;prefix&gt;foo&quot;).
        &#39;!&lt;foo&gt;&#39;: Verbatim tag (always means &quot;foo&quot;).

Why is it relevant to have a primary and secondary tag, and why does a secondary tag refer to a URI?  What problem is being solved by having these?

I seem to see a lot of &quot;what they are&quot;, and no &quot;why are they there&quot;, or &quot;what are they used for&quot;.

I don&#39;t understand what a YAML tag is

So basically I am looking for good templates for writing both technical and functional specs on a project or work request.

What do you use? How deep do you get while writing the specs? Any additional general tips you could provide would be appreciated.

My company needs these badly. I work for a contractor and right now we do not use these documents at all. 

**EDIT:** I have read Joel&#39;s take about [Painless Specification][1], I really liked it, but are there any other opinions :) 


  [1]: http://www.joelonsoftware.com/articles/fog0000000036.html

Templates of Technical and Functional Specs

I am using rSpec for testing my application.  In my application controller I have a method like so:

    def set_current_account
      @current_account ||= Account.find_by_subdomain(request.subdomains.first)
    end

Is it possible to set the request.subdomain in my spec?  Maybe in the before block?  I am new to rSpec so any advice on this would be great thanks.

Eef



Rails rspec set subdomain

I discovered that you can start your variable name with a &#39;@&#39; character in C#. 
In my C# project I was using a web service (I added a web reference to my project) that was written in Java. One of the interface objects defined in the WSDL had a member variable with the name &quot;params&quot;. Obviously this is a reserved word in C# so you can&#39;t have a class with a member variable with the name &quot;params&quot;. The proxy object that was generated contained a property that looked like this:

    public ArrayList @params {
        get { return this.paramsField; }
        set { this.paramsField = value; }
    }

I searched through the VS 2008 c# documentation but couldn&#39;t find anything about it. Also searching Google didn&#39;t give me any useful answers. So what is the exact meaning or use of the &#39;@&#39; character in a variable/property name?

What&#39;s the use/meaning of the @ character in variable names in C#?

I wish HTML could do something semantically equivalent to this;

    &lt;dl class=&quot;main-list&quot;&gt;
        &lt;definitionitem&gt;
            &lt;dt&gt;Some Thing&lt;/dt&gt;
                &lt;dd&gt;You know it!&lt;/dd&gt;
            &lt;dt&gt;Another Thing&lt;/dt&gt;
                &lt;dd&gt;Word.&lt;/dd&gt;
        &lt;/definitionitem&gt;
        &lt;definitionitem&gt;
            &lt;dt&gt;Stuff&lt;/dt&gt;
                &lt;dd&gt;Alright!&lt;/dd&gt;
        &lt;/definitionitem&gt;
    &lt;/dl&gt;

However, since the closest I&#39;ve come is something I&#39;m not 100% satisfied with the semantics of;

    &lt;div class=&quot;redundant-wrapper&quot;&gt;
        &lt;dl class=&quot;main-list&quot;&gt;
            &lt;dt&gt;Some Thing&lt;/dt&gt;
                &lt;dd&gt;You know it!&lt;/dd&gt;
            &lt;dt&gt;Another Thing&lt;/dt&gt;
                &lt;dd&gt;Word.&lt;/dd&gt;
        &lt;/dl&gt;
        &lt;dl class=&quot;another-main-list&quot;&gt;
            &lt;dt&gt;Stuff!&lt;/dt&gt;
                &lt;dd&gt;Alright!&lt;/dd&gt;
        &lt;/dl&gt;
    &lt;/div&gt;

I was wondering if anyone has any other ideas of how you might do this?

Also, the reason the items would be grouped is because they are visually grouped in the content that is being marked up. Imagine a dictionary page, with a single definition list, where each definition is in an inset box that is floated left. I run into this situation all the time.

All Specifications Solutions on Gang of Coders

Total of 22 Specifications Solutions

Why is form enctype=multipart/form-data required when uploading a file?

Fetch API - What's the use of redirect: manual

Why are await and async valid variable names?

Do the JSON keys have to be surrounded by quotes?

Do UNIX timestamps change across timezones?

How to encode the filename parameter of Content-Disposition header in HTTP?

What does the @ symbol before a variable name mean in C#?

Any reason to write the "private" keyword in C#?

What's valid and what's not in a URI query?

enum.values() - is an order of returned enums deterministic

Java's L number (long) specification

What is the value of the css 'ex' unit?