javascript replace dash char using regex or otherwise

Question

I have this:

11111-22222-333---444---55--5566--6-----7-

I am using this code:

overlaps.replace(/-{2}/g, '-');

however it does not work, want i am looking for is that multiple instances of - should be replaced with one - and ending dash should be removed if any.

Can anybody tell what i am doing wrong ?

To explain why your version does not work : replace will scan the string from left to right replacing each occurrence of matching strings. The scan will continue from immediately beyond the replaced string. Hope that helps. — HBP
– HBP, Commented May 18, 2012 at 13:47

Dagg Nabbit · Accepted Answer · 2012-05-18 13:39:23Z

4

There's no need to use two regular expressions. This should work fine.

overlaps.replace(/-+$|(-)+/g, '$1')

http://jsfiddle.net/wJLTB/3/

answered May 18, 2012 at 13:39

Dagg Nabbit

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3 Comments

kalisjoshua Over a year ago

+1 I love it. This is way better than my multiple replace calls. My regex has gotten rusty due to infrequent use.

Dagg Nabbit Over a year ago

@kalisjoshua sometimes multiple simple regex will perform better than a single complex one... it's worth testing for performance-critical things.

VisioN Over a year ago

@GGG I was thinking about the same (about last comment). However, possibly replace callback might be even faster. Really worth testing.

kalisjoshua · Accepted Answer · 2012-05-18 13:31:29Z

1

Close but forgot the final condition:

and ending dash should be removed if any.

So use this instead:

overlaps.replace(/-+/g, "-").replace(/-+$/, "");

answered May 18, 2012 at 13:31

kalisjoshua

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Comments

VisioN · Accepted Answer · 2012-05-18 13:40:58Z

1

You can use:

overlaps.replace(/-+/g, "-").replace(/-$/, "");

DEMO: http://jsfiddle.net/wJLTB/1/

Another way is to use callback function:

overlaps.replace(/-+/g, function(str, p1, offset) {
    return offset.lastIndexOf("-") == p1 ? "" : "-";
})

DEMO: http://jsfiddle.net/wJLTB/2/

edited May 18, 2012 at 13:40

answered May 18, 2012 at 13:28

VisioN

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Comments

georg · Accepted Answer · 2012-05-18 13:52:37Z

0

This looks cleaner to me:

overlaps.replace(/-(?=-|$)/g, '')

The expr reads: remove dash followed by another dash or by the end of input.

answered May 18, 2012 at 13:52

georg

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1 Comment

Dagg Nabbit Over a year ago

The lookahead is almost guaranteed to be slower, though. Looks like it's jsperf time. (edit: looks like it's not jsperf time, jsperf is down right now. Maybe it will be jsperf time later).

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