String reverse in javascript using prototype

Question

String.prototype.reverseStr = function () {
    var len = this.length - 1;
    var j = 0;
    for (i = len; i >= Math.floor(len / 2); i--) {
        var tmp = this[i];
        this[i] = this[j];
       this[j] = tmp;
       j++;
    }
    return this;
}

alert("abcde".reverseStr());

Why doesn't this work ? It outputs "abcde" and not reversed string .

SeanCannon · Accepted Answer · 2015-01-16 01:00:30Z

2

Overkill.

 "abcde".split('').reverse().join('');

answered Jan 16, 2015 at 1:00

SeanCannon

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3 Comments

Josh Crozier Over a year ago

1+ And it's surprisingly faster than most other methods too. (at least in modern browsers). jsperf.com/string-reverse/4

Vidya Over a year ago

I got this . But what if I have write my own string function. Why doest the above code work.

elclanrs Over a year ago

@rrmo, Strings are immutable.

elclanrs · Accepted Answer · 2015-01-16 08:32:29Z

-1

The same code but with some edits

String.prototype.reverseStr = function () {
    var len = this.length - 1;
    var tmp = '';
    for (var i = len; i >= 0; i--) {
        tmp += this[i];
    }
    return tmp;
}

alert("abcde".reverseStr());

See a fiddle here

edited Jan 16, 2015 at 8:32

elclanrs

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answered Jan 16, 2015 at 1:05

jpcanamaque

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