Object methods assigned to variables or function arguments fail when invoked

Question

I\'m learning javascript right now, seems like beautiful functional language to me, it is wonderful move from PHP, I should have done this earlier. Although, I cannot figure

Answer 1

If you store just a method, it does not carry with it a reference to your object - it just stores a reference to the .test method, but no particular object. Remember, a method is "just" a property on an object and storing a reference to a method doesn't bind it to that object, it just stores a reference to the method.

To invoke that method on a particular object, you have to call it with that object.

You can make your own function that calls the method on the desired object like this:

var v1 = function(x) {
    return /[abc]/.test(x);
}

Then, when you do this:

v1('a');

It will execute the equivalent of this in your function:

/[abc]/.test('a');

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But, it isn't entirely clear why you're doing that as you could also just define the regex and call .test() on it several times:

var myRegex = /[abc]/;
console.log(myRegex.test('a'));
console.log(myRegex.test('b'));
console.log(myRegex.test('z'));