How do I remove part of a string in JavaScript?

Question

I'm trying to write a function that works like

"aaaabbccccdeeeaaaaa" --> "abcdea"

but I can't figure out how to actually remove characters from the string. So where I'm at is

String.prototype.removeConsecutives = function()
{
      let k = 0;
    for(int i = 0; i < this.length; ++i)
        if(this[i] !== this[i-1])
          this[k++] = this[i];
    // now I want to remove the characters in the range
    // of indices [k, this.length)
}

Two things: don't modify built-in properties (you might touch something you didn't know was there), and don't try to modify a string in place (it won't work). — John Dvorak, Jul 19 '16 at 05:05
You shoul use charAt(i) instead of[i]. A regex is a better option. — Krishnakumar_Muraleedharan, Jul 19 '16 at 05:11
@Krishnakumar_Muraleedharan what is the benefit of using `charAt` over `[]`? — zerkms, Jul 19 '16 at 05:12
@zerkms, substring, substr or charAt are the only ways in JS to refer to a character in string — Krishnakumar_Muraleedharan, Jul 19 '16 at 05:16
@Krishnakumar_Muraleedharan surely, `[]` is a way to access a character in JS — zerkms, Jul 19 '16 at 05:16
@Krishnakumar_Muraleedharan - You forgot `.slice()`. And `.split("")[i]`. — nnnnnn, Jul 19 '16 at 05:19
@zerkms: I mean [it *was* a benefit](http://stackoverflow.com/q/5943726/1048572) back in the days when IE7 was relevant :-) — Bergi, Jul 19 '16 at 05:19

nnnnnn · Answer 1 · 2016-07-19T05:18:32.880

2

This is easy with a regex replace:

var result = "aaaabbccccdeeeaaaaa".replace(/(.)\1+/g,"$1");

console.log(result);

In the regex I've shown, (.) matches any character, and then \1 is a back-reference to whatever matched in the parentheses with + meaning one or more of those. Do a global replace with the g flag. And the replacement string uses $1 to use the sub-match in parentheses.

edited Jul 19 '16 at 05:18

answered Jul 19 '16 at 05:13

nnnnnn

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How do I remove part of a string in JavaScript?

1 Answers1