Hidden Features of JavaScript? [closed]

Answer 1

"Extension methods in JavaScript" via the prototype property.

Array.prototype.contains = function(value) {  
    for (var i = 0; i < this.length; i++) {  
        if (this[i] == value) return true;  
    }  
    return false;  
}

This will add a contains method to all Array objects. You can call this method using this syntax

var stringArray = ["foo", "bar", "foobar"];
stringArray.contains("foobar");