When looking at the sourcecode for a tslint rule, I came across the following statement:

    if (node.parent!.kind === ts.SyntaxKind.ObjectLiteralExpression) {
        return;
    }

Notice the `!` operator after `node.parent`. Interesting!

I first tried compiling the file locally with my currently installed version of TS (1.5.3). The resulting error pointed to the exact location of the bang:

    $ tsc --noImplicitAny memberAccessRule.ts 
    noPublicModifierRule.ts(57,24): error TS1005: &#39;)&#39; expected.

Next I upgraded to the latest TS (2.1.6), which compiled it without issue. So it seems to be feature of TS 2.x. **But** the transpilation ignored the bang completely, resulting in the following JS:

    if (node.parent.kind === ts.SyntaxKind.ObjectLiteralExpression) {
        return;
    }

My Google fu has thus far failed me. 

**_What is TS&#39;s exclamation mark operator, and how does it work?_**

  [1]: https://github.com/palantir/tslint/blob/master/src/rules/memberAccessRule.ts#L96
  [2]: https://github.com/Microsoft/TypeScript/issues/16

In Typescript, what is the ! (exclamation mark / bang) operator when dereferencing a member?

The `// @ts-ignore` comment enables the TypeScript compiler to ignore the line below it.

How can one ignore a whole block of code with TypeScript?

How to use `@ts-ignore` for a block?

Lint error message: 

&gt; src/app/detail/edit/edit.component.ts[111, 5]: for (... in ...)
&gt; statements must be filtered with an if statement

Code snippet (It is a working code. It is also available at [angular.io form validation section][1]):
 

    for (const field in this.formErrors) {
          // clear previous error message (if any)
          this.formErrors[field] = &#39;&#39;;
          const control = form.get(field);
    
          if (control &amp;&amp; control.dirty &amp;&amp; !control.valid) {
            const messages = this.validationMessages[field];
            for (const key in control.errors) {
              this.formErrors[field] += messages[key] + &#39; &#39;;
            }
          }
        }

Any idea how to fix this lint error?

  [1]: https://angular.io/docs/ts/latest/cookbook/form-validation.html

tslint / codelyzer / ng lint error: &quot;for (... in ...) statements must be filtered with an if statement&quot;

I recently started seeing, what seems like, TSLint errors.
They look like this:

&gt; Not using the local TSLint version found for 
&#39;/Users/myname/myproject/client/src/app/likes/likee/likee.component.ts&#39;.
To enable code execution from the current workspace you must enable workspace library execution.

I&#39;m seeing them in my .ts files when I open them and it shows a yellow squiggly line on the first line of each .ts page.

I see on the [TSLint][1] site it says it&#39;s been deprecated. 

**QUESTION 1** - What&#39;s the cause of these errors and why am I suddenly seeing them?

**QUESTION 2** - Should I uninstall the Visual Studio Code TSLint extension and install the ESLint extension?


  [1]: https://www.npmjs.com/package/tslint

TSLint extension throwing errors in my Angular application running in Visual Studio Code

When I run the linter it says:

    subscribe is deprecated: Use an observer instead of an error callback

Code (from an angular 7 app with angular-cli):

```typescript
    this.userService.updateUser(data).pipe(
       tap(() =&gt; {bla bla bla})
    ).subscribe(
       this.handleUpdateResponse.bind(this),
       this.handleError.bind(this)
    );
```

Don&#39;t know exactly what should I use and how...

Thanks!

Subscribe is deprecated: Use an observer instead of an error callback

The IDE being used is WebStorm 11.0.3, the tslint is configured and works, but, it hangs because it tries to parse large *.d.ts library files. 

Is there a way to ignore a particular file or directory?

How to ignore a particular directory or file for tslint?

I just started using create-react-app with typescript 

    create-react-app my-app --scripts-version=react-scripts-ts

and the default tslint.json configuration does not allow console.log().

**How can I (for now) enable console.log?**  

The docs for this are at  [https://palantir.github.io/tslint/rules/no-console/][1].  But they don&#39;t say where to put this line:

        &quot;no-console&quot;: [true, &quot;log&quot;, &quot;error&quot;]

I searched and found this [tslint.json configuration file syntax][2], so I tried this:

    &quot;rules&quot;: {
        &quot;no-console&quot;: [true, &quot;warning&quot;]
    }

In an attempt to get log messages that would just be warnings.
But that didn&#39;t work.

I&#39;ve commented out the few console.log() lines I have but will want to be able to do this in the future.


  [1]: https://palantir.github.io/tslint/rules/no-console/
  [2]: https://palantir.github.io/tslint/usage/configuration/

tslint says calls to console.log are not allowed - How do I allow this?

I&#39;m using tslint, and got the error.  

    &#39;myVariable&#39; is declared but its value is never read.

I went to the website that documents the rules [https://palantir.github.io/tslint/rules/][1] and searched for the string ```is declared but its value is never read``` but didn&#39;t find that text.  While I can and did look for settings that might be tied to this error, it shouldn&#39;t be a guessing game.

**What is the configuration change needed to suppress/stop this error?**

Just as importantly, **when I get an error in tslint that says &quot;this happened&quot; how can I find what setting is used to configure or change the tslint behavior on how to handle that error?**

I also did a search on the website (google search I used was)

    site:palantir.github.io  is declared but its value is never read 

but a direct hit did not appear, so the answer might be on the palantir.github.io website but I just didn&#39;t (yet) find it.

**How do others find the tslint variable/configuration settings that change to suppress a particular error?**

Please refrain from suggesting I comment out the code that is causing the problem.  I&#39;m looking for an answer to my more general question as well as to the specific question.  Thank you.

  [1]: https://palantir.github.io/tslint/rules/

tslint how to disable error &quot;someVariable is declared but its value is never read&quot;

I know that it is not ideal to reload an Angular Single Page Application. However there is a place that I need to reload the full application.

TSLint says that reload is deprecated.

Is there any alternative for this? 

location.reload(true) is deprecated

I&#39;m doing some basic asynchronous operations using `async/await` in TypeScript but TSLint is throwing mysterious error messages for these two functions below. Has anyone encountered these errors before? On the error output the governing rule is not mentioned, so I don&#39;t understand what&#39;s causing these. Any ideas would be greatly appreciated.

The main request:

    import * as rp from &#39;request-promise&#39;
    
    export function getRequest(address: rp.Options): rp.RequestPromise {
      return rp(address)
    }


Exported async function:  

    export async function getStatus(message: Message) {
      try {
        const res = await getRequest(address)
        if (res.ready) {
          message.reply(&#39;...&#39;)
        } else {
          message.reply(&#39;...&#39;)
        }
      } catch (err) {
        message.reply(err)
      }
    }

This gets: `Promises must be handled appropriately`and `await of non-Promise` for line #3.

The simple function that uses this export is:

    client.on(&#39;message&#39;, message =&gt; {
      if (message.content === &#39;green&#39;) {
        getStatus(message)
      }
    })

This also gets `Promises must be handled appropriately`.

Additional information:

Even though the error message doesn&#39;t mention it, this seems to be the governing rule for `Promises must be handled appropriately`:
https://palantir.github.io/tslint/rules/no-floating-promises/

And this Issue mentions `await of non-Promise`:
https://github.com/palantir/tslint/issues/2661


What could this be about? [TsLint Error: &quot;Promises must be handled appropriately&quot;]

I&#39;m pretty new to TypeScript and I would like to know if there exists a good way to rewrite code to avoid TSLint error &quot;object access via string literals is disallowed&quot; in the following code

    interface ECType
    {
        name: string;
        type: string;
        elementType?: string;
    }

    export var fields: { [structName: string]: Array&lt;ECType&gt;; } = { };

    class ECStruct1 {
        foo: string;
        bar: number;
        baz: boolean;
        qux: number;
        quux: number;
        corge: ECStruct2[];
        grault: ECStruct2;

        constructor() {
            ...
        }
    } 

    fields[&#39;ECStruct1&#39;] = [
        { name: &#39;foo&#39;, type: &#39;string&#39; },
        { name: &#39;bar&#39;, type: &#39;int&#39; },
        { name: &#39;baz&#39;, type: &#39;bool&#39; },
        { name: &#39;qux&#39;, type: &#39;long&#39; },
        { name: &#39;quux&#39;, type: &#39;ulong&#39; },
        { name: &#39;corge&#39;, type: &#39;array&#39;, elementType: &#39;ECStruct2&#39; },
        { name: &#39;grault&#39;, type: &#39;ECStruct2&#39; }
    ];

**Update**: At the end the content above will be part of a self-generated file with more than 300 `ECStruct`s, so I would like to have the class definition (e.g. `ECStruct1`) followed by its meta-description (e.g. `fields[&#39;ECStruct1&#39;]`).


How to rewrite code to avoid TSLint &quot;object access via string literals&quot;

I have a function in my code:

    networkStop = (action: string = null) =&gt; {
        this.action[action] = false;
        this.net = false;
        this.netd = false;
    }

I&#39;m getting a TsLint error saying:

    Message	4	TsLint: expected callSignature to have a typedef.

	

Can someone explain what this means?

What does it mean when TsLint says &quot;expected callSignature to have a typedef.&quot;

I notice in my application that TsLint is suggesting:

    static $inject = [
            &#39;$http&#39;,
            &#39;$q&#39;,
            &#39;$scope&#39;,
            &#39;configService&#39;,
            &#39;stateService&#39;,
            &#39;utilityService&#39;
        ];

for the above that:

    Message	2	TsLint: &#39; should be &quot;

Is this a suggested standard now for Typescript ?



What is the standard for use of quotes in Typescript?

        [64, 1]: space indentation expected
        [15, 27]: Missing semicolon
        [109, 36]: missing whitespace
        [111, 24]: missing whitespace
        [70, 1]: Consecutive blank lines are forbidden

I keep getting warnings like these  from TSLint. There are huge amount of warnings, and it will be very difficult to fix it manually.

I was looking for a way which can **auto-fix** most of the warnings.

Auto fix TSLint Warnings

In my Angular2 App I&#39;m importing one component like this:

    import { PersonsSingleAccountComponent} from 
       &#39;../persons-information/fragments/persons-single-account/persons-single-account-bookings/persons-single-account-bookings.component&#39;

It is giving me the lint error &quot;Exceeds maximum line character&quot;. If I try to give the statement in ``(backtick) it is throwing an error.

How can I solve this lint error?

TSLint Error &quot;Exceeds maximum line length of 120&quot;

So this feels like this should be such an easy task but it&#39;s starting to drive me insane. I can&#39;t seem to turn off TSLint or TS or whatever it is that gives me these errors. I just want the ESLint with my own configured rules, nothing else.

[![I only want the ESLint error][1]][1]


  [1]: https://i.stack.imgur.com/PlKpX.png


Is it built in TS? I have disabled TSLint extension (even uninstalled it). I have set the following rules:

    &quot;typescript.format.enable&quot;: false,
    &quot;typescript.validate.enable&quot;: false,

Still gives me error. How do I turn this off?

Disable TSLint in VSCode

Is that possible to lint entire folder using tslint?

Using eslint it is possible to do `eslint ./src` to validate whole folder. 

When i try to do the same for tslint - i am getting an error `Error: EISDIR: illegal operation on a directory`. In their examples on the site - they show how to validate single file, which is not the case usually.

Is that possible to validate my project without extra things like `gulp-tslint`, just from the command line?

How to lint entire folder using tslint

I currently have an issue with tslint and was hoping someone could point me in the right direction.

I&#39;m trying to send an HTTP GET request using HTTP provided by the Angular2 framework. With this request, I must specify the content-type and the bearer authentication token.

Example of my code:

    let headers = new Headers();
    let authToken = this._user.getUser().JWT;
    headers.append(&#39;Content-Type&#39;, &#39;application/json&#39;);
    headers.append(&#39;Authorization&#39;, `Bearer ${authToken}`);
    let options = new RequestOptions({ headers: headers });

    this._http.get(&#39;http://&#39; + url &#39;/&#39;, options)
                .timeout(3000)
                .subscribe(
                    (res) =&gt; {

This works, however, tslint is complaining that 

&gt; &quot;TS2345: Argument of type &#39;{ headers: Headers; }&#39; is not assignable to
&gt; parameter of type &#39;RequestOptionsArgs&#39;. Types of property &#39;headers&#39;
&gt; are incompatible. Type &#39;Headers&#39; is not assignable to type &#39;Headers&#39;.
&gt; Two different types with this name exist, but they are unrelated.
&gt; Property &#39;keys&#39; is missing in type &#39;Headers&#39;.&quot;

I appreciate the support.

Angular2 - HTTP RequestOptions HEADERS

From time to time, I get TSLint errors &quot;block is empty&quot;. This happens e.g. when I pass a no-op callback to a function:

    doSomething(() =&gt; {});

From what I read, JSLint apparently does the same, but I didn&#39;t verify that.

I find these usages completely valid, so I tried to find a reason why empty blocks are considered bad at all. But the only thing I&#39;m able to find (e.g. in [this answer](https://stackoverflow.com/a/17685875/219187)) are instructions to add a `return;` to avoid the error. This is **not** what I want to do in every empty callback.

Why does TSLint report above empty block as problem? Is there any reason why I shouldn&#39;t disable the check?

Why do TSLint and JSLint report empty blocks?

I have got a tslint error to my for loop when I try to resolve it it says to convert to for-of. I have seen many docs but its not helpful.How can I solve the lint error and I cannot do tslint:disable-next-line:prefer-for-of

    for (let i = 0; i &lt; this.rows.length; ++i) {
        if (!this.rows[i].selected) {
            this.selectAllChecked = false;
            break;
        }
    }



[tslint]Expected a &#39;for-of&#39; loop instead of a &#39;for&#39; loop with this simple iteration (prefer-for-of)

I have some variable names starting with leading underscore , I still get this warning after updating my tslint.json

**tslint.json**

	{
	  &quot;extends&quot;: &quot;tslint:recommended&quot;,
	  &quot;rules&quot;: {
	    &quot;variable-name&quot;: [
	      true,
	      &quot;ban-keywords&quot;,
	      &quot;check-format&quot;,
	      &quot;allow-leading-underscore&quot;
	    ]
	  },
	  &quot;exclude&quot;: [
	    &quot;build/**/*&quot;,
	    &quot;node_modules/**/*&quot;,
	    &quot;tmp/**/*&quot;
	  ]
	}
where am I wrong ?

thanks for feedback

UPDATE 

I am using version 4.5.1 of TSLint


All Tslint Solutions on Gang of Coders

Total of 21 Tslint Solutions

In Typescript, what is the ! (exclamation mark / bang) operator when dereferencing a member?

How to use `@ts-ignore` for a block?

tslint / codelyzer / ng lint error: "for (... in ...) statements must be filtered with an if statement"

TSLint extension throwing errors in my Angular application running in Visual Studio Code

Subscribe is deprecated: Use an observer instead of an error callback

How to ignore a particular directory or file for tslint?

tslint says calls to console.log are not allowed - How do I allow this?

tslint how to disable error "someVariable is declared but its value is never read"

location.reload(true) is deprecated

What could this be about? [TsLint Error: "Promises must be handled appropriately"]

How to rewrite code to avoid TSLint "object access via string literals"

What does it mean when TsLint says "expected callSignature to have a typedef."

What is the standard for use of quotes in Typescript?

Auto fix TSLint Warnings

TSLint Error "Exceeds maximum line length of 120"

Disable TSLint in VSCode

How to lint entire folder using tslint

Angular2 - HTTP RequestOptions HEADERS

Why do TSLint and JSLint report empty blocks?

[tslint]Expected a 'for-of' loop instead of a 'for' loop with this simple iteration (prefer-for-of)

TSLint : variable name must be in camelcase or uppercase