Simple solution:

var str = ball, apple, mouse, kindle;

var hasApple = str.indexOf('apple') != -1;

However, that will also match if str contains apple fritters:

var str = ball, apple fritters, mouse, kindle;

var hasApple = str.indexOf('apple') != -1; // true

There are different approaches you could do to get more specific. One would be to split the string on commas and then iterate through all of the parts:

var splitString = str.split(',');

var appleFound;

for (var i = 0; i < splitString.length; i++) {

    var stringPart = splitString[i];

    if (stringPart != 'apple') continue;



    appleFound = true;

    break;

}

NOTE: You could simplify that code by using the built-in some method, but that's only available in newer browsers. You could also use the Underscore library which provides its own some method that will work in any browser.

Alternatively you could use a regular expression to match apple specifically:

var appleFound = /Wapple,/.test(',' + str + ',');

However, I think your real best bet is to not try and solve this yourself. Whenever you have a problem like this that is very common your best bet is to leverage an existing library. One example would be the Underscore String library, especially if you're already using Underscore. If not, there are other general purpose string utility (eg. String.js) libraries out there you can use instead.