Check if string begins with something?
JavascriptStringMatchJavascript Problem Overview
I know that I can do like ^=
to see if an id starts with something, and I tried using that for this, but it didn't work. Basically, I'm retrieving a URL and I want to set a class for an element for path names that start in a certain way.
Example:
var pathname = window.location.pathname; //gives me /sub/1/train/yonks/459087
I want to make sure that for every path that starts with /sub/1
, I can set a class for an element:
if (pathname ^= '/sub/1') { //this didn't work...
...
Javascript Solutions
Solution 1 - Javascript
if (pathname.substring(0, 6) == "/sub/1") {
// ...
}
Solution 2 - Javascript
String.prototype.startsWith = function(needle)
{
return this.indexOf(needle) === 0;
};
Solution 3 - Javascript
You can use [string.match()][1] and a regular expression for this too:
if(pathname.match(/^\/sub\/1/)) { // you need to escape the slashes
string.match()
will return an array of matching substrings if found, otherwise null.
[1]: http://www.w3schools.com/jsref/jsref_match.asp "string.match"
Solution 4 - Javascript
A little more reusable function:
beginsWith = function(needle, haystack){
return (haystack.substr(0, needle.length) == needle);
}
Solution 5 - Javascript
First, lets extend the string object. Thanks to Ricardo Peres for the prototype, I think using the variable 'string' works better than 'needle' in the context of making it more readable.
String.prototype.beginsWith = function (string) {
return(this.indexOf(string) === 0);
};
Then you use it like this. Caution! Makes the code extremely readable.
var pathname = window.location.pathname;
if (pathname.beginsWith('/sub/1')) {
// Do stuff here
}
Solution 6 - Javascript
Have a look at JavaScript substring()
method.