In javascript, how do you search an array for a substring match

If you're able to use Underscore.js in your project, the _.filter() array function makes this a snap:

// find all strings in array containing 'thi'
var matches = _.filter(
    [ 'item 1', 'thing', 'id-3-text', 'class' ],
    function( s ) { return s.indexOf( 'thi' ) !== -1; }
);

The iterator function can do whatever you want as long as it returns true for matches. Works great.

Update 2017-12-03:
This is a pretty outdated answer now. Maybe not the most performant option in a large batch, but it can be written a lot more tersely and use native ES6 Array/String methods like .filter() and .includes() now:

// find all strings in array containing 'thi'
const items = ['item 1', 'thing', 'id-3-text', 'class'];
const matches = items.filter(s => s.includes('thi'));

Note: There's no <= IE11 support for String.prototype.includes() (Edge works, mind you), but you're fine with a polyfill, or just fall back to indexOf().

People here are making this waaay too difficult. Just do the following...

myArray.findIndex(element => element.includes("substring"))

findIndex() is an ES6 higher order method that iterates through the elements of an array and returns the index of the first element that matches some criteria (provided as a function). In this case I used ES6 syntax to declare the higher order function. element is the parameter of the function (which could be any name) and the fat arrow declares what follows as an anonymous function (which does not need to be wrapped in curly braces unless it takes up more than one line).

Within findIndex() I used the very simple includes() method to check if the current element includes the substring that you want.