确定数组是否包含值

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;

};

您可以像这样使用它：

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