Javascript String Object V.S. just string

Question

OK, first, i'm not going to seek a method to convert the Object to String.

but i'm facing a problem like this:

String.prototype.foo = function() {
    return this;
};

var rawString = "abcde";

var fooString = "abcde".foo();

console.log(typeof(rawString) + ': ', rawString);
console.log(typeof(fooString) + ': ', fooString);

or jsfiddle you preferred.

also, a screenshot is attached:

the strange thing in Javascript.

as you can see, i did almost nothing in the prototype method foo, i just return this.

but the result of typeof are totally different

Why is this? how can i just return abcde rather thant {0: "a"...} ?

Thanks!

possible duplicate of Javascript WTF: a String.prototype's "this" doesn't return a string? — Crescent Fresh
– Crescent Fresh, Commented Aug 18, 2012 at 16:59
@CrescentFresh oops, you're right. i tried to search, but i didn't make it. sorry for the duplicate question. — Ya Zhuang
– Ya Zhuang, Commented Aug 18, 2012 at 17:23

jAndy · Accepted Answer · 2012-08-18 17:02:24Z

5

The this references the String Object, so you need to return it like

return this.toString();

which in turn, creates the primitive string version and returns it.

answered Aug 18, 2012 at 17:02

jAndy

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2 Comments

Ya Zhuang Over a year ago

great! thanks!! but feel so strange to write the "string".toString() .. LOL, odd javascript.

ted Over a year ago

@bitsMix, it's an object oriented language

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