Determine whether an array contains a value

This question already has an answer here:

How do I check if an array includes an object in JavaScript? 40 answers

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var contains = function(needle) {
    // Per spec, the way to identify NaN is that it is not equal to itself
    var findNaN = needle !== needle;
    var indexOf;

    if(!findNaN && typeof Array.prototype.indexOf === 'function') {
        indexOf = Array.prototype.indexOf;
    } else {
        indexOf = function(needle) {
            var i = -1, index = -1;

            for(i = 0; i < this.length; i++) {
                var item = this[i];

                if((findNaN && item !== item) || item === needle) {
                    index = i;
                    break;
                }
            }

            return index;
        };
    }

    return indexOf.call(this, needle) > -1;
};

You can use it like this:

var myArray = [0,1,2],
    needle = 1,
    index = contains.call(myArray, needle); // true

CodePen validation/usage

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jQuery has a utility function for this:

$.inArray(value, array)

Returns index of value in array . Returns -1 if array does not contain value .

See also How do I check if an array includes an object in JavaScript?

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This is generally what the indexOf() method is for. You would say:

return arrValues.indexOf('Sam') > -1

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