Why doesn't JavaScript let you call methods on numbers directly?

Question

In Ruby, you can do this:

3.times { print "Ho! " } # => Ho! Ho! Ho!

I tried to do it in JavaScript:

Number.prototype.times = function(fn) {
    for (var i = 0; i < this; i++) {
        fn();
    }
}

This works:

(3).times(function() { console.log("hi"); });

This doesn't

3.times(function() { console.log("hi"); });

Chrome gives me a syntax error: "Unexpected token ILLEGAL". Why?

... Because JavaScript isn't Ruby? That's like asking "Why doesn't cobol work like Ruby?". — Incognito, Sep 04 '12 at 23:29
@Incognito um, no? I'm asking why it's a syntax error, not why it doesn't work like ruby... — Alex Coplan, Sep 04 '12 at 23:30
Can you explain the rational behind talking about ruby in the first place and maintain consistency with that statement? — Incognito, Sep 04 '12 at 23:31
@Incognito I wanted to re-create that method, so I just mentioned what I was trying to achieve. — Alex Coplan, Sep 04 '12 at 23:33
@Incognito obviously Ruby is a bad thing to bring up in a JS question so I won't bother with that again... — Alex Coplan, Sep 04 '12 at 23:34

Musa · Accepted Answer · 2013-12-29T21:37:13.827

37

The . after the digits represents the decimal point of the number, you'll have to use another one to access a property or method.

3..times(function() { console.log("hi"); });

This is only necessary for decimal literals. For octal and hexadecimal literals you'd use only one ..

03.times(function() { console.log("hi"); });//octal
0x3.times(function() { console.log("hi"); });//hexadecimal

Also exponential

3e0.times(function() { console.log("hi"); });

You can also use a space since a space in a number is invalid and then there is no ambiguity.

3 .times(function() { console.log("hi"); });

Although as stated by wxactly in the comments a minifier would remove the space causing the above syntax error.

edited Dec 29 '13 at 21:37

answered Sep 04 '12 at 23:20

Musa

Ah, thanks. Interesting that it can also represent a decimal point in Ruby but it still works. – Alex Coplan Sep 04 '12 at 23:21
5

I go against doing 2 dots since it is very likely to create confusion for the reader. Parantheses are more self descriptive. – Umur Kontacı Sep 04 '12 at 23:27
3

@AlexCoplan I'm guessing because Ruby has integer and float types, but JavaScript just has Number – Musa Sep 04 '12 at 23:30
2

The last example utilizing a space is interesting to know, but unsafe to rely on... When you run that code through a minifier, BAM your syntax error shows up again. – wxactly Dec 29 '13 at 21:05

1 Answers1