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

The test function expects this to be a regular expression. The expression /[abc]/.test gives an unbound function (it does not remember that it belongs to /[abc]/). When you invoke it like you do, this will be undefined and the function will fail.

You can use bind to make the function remember the object it belongs to:

var v1 = /[abc]/.test.bind(/[abc]/);

or

var v1 = RegExp.prototype.test.bind(/[abc]/);