Javascript replace() and regex

Question

Im trying to use javascript and regex to replace a substring in a url.

myurl.com/?page_id=2&paged=2

shall become

myurl.com/?page_id=2&paged=3

this is my code that doesnt seem to work:

nextLink = 'myurl.com/?page_id=2&paged=2'
nextLink = nextLink.replace(/\/paged\=\/[0-9]?/, 'paged='+ pageNum);

What am i doing wrong here? Im new to regex.

T.J. Crowder · Accepted Answer · 2012-11-03 17:25:01Z

2

You're telling it to match /paged, but there's no /paged in your string. Also, [0-9]? probably isn't what you want for the digits. Try this:

nextLink.replace(/\&paged=[0-9]+/, 'paged=' + pageNum);

That tells it to replace &pageid=... (where ... is a series of one or more digits) with the given string.

answered Nov 3, 2012 at 17:25

T.J. Crowder

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2 Comments

gdoron Over a year ago

+1, I would add a note about what kind of chars needs to be escaped.

Viktor Over a year ago

Both answers works like a charm, just missed out on the '&' in the second argument. Thanks!

Bergi · Accepted Answer · 2012-11-03 17:23:38Z

1

You don't need to escape the =, and you have some additional slashes to match that don't exist in your sample url. Without them, it should work:

nextLink = nextLink.replace(/[?&]paged=[0-9]?/, 'paged='+ pageNum);

answered Nov 3, 2012 at 17:23

Bergi

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Comments

Lightness Races in Orbit · Accepted Answer · 2012-11-03 17:24:43Z

1

Yours:

nextLink = nextLink.replace(/\/paged\=\/[0-9]?/, 'paged='+ pageNum);

Mine:

nextLink = nextLink.replace(/&paged=[0-9]?/, 'paged='+ pageNum);

i.e. you wrote \/ when you meant &. You also wrote it before the digits for some reason. And you don't need to escape =.

answered Nov 3, 2012 at 17:24

Lightness Races in Orbit

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Comments

phant0m · Accepted Answer · 2012-11-03 17:33:41Z

1

Why use regular expressions, when you can use the excellent URI.js library?

URI("myurl.com/?page_id=2&paged=2")
    .removeQuery("paged")  // remove so we don't have a duplicate
    .addQuery("paged", pageNum)
    .toString();

You don't need to worry about escaping, URI.js does everything for you.

answered Nov 3, 2012 at 17:33

phant0m

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Ωmega · Accepted Answer · 2012-11-03 17:42:07Z

1

Use callback function:

var r = new RegExp("paged=(\\d+)");
s = s.replace(r, function($1, $2){ return "paged=" + (parseInt($2, 10) + 1); });

See this demo.

edited Nov 3, 2012 at 17:42

answered Nov 3, 2012 at 17:36

Ωmega

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Comments

Martin Ender · Accepted Answer · 2012-11-03 17:22:53Z

0

Too many slashes. \/ will try to match a literal slash which is not there:

nextLink = nextLink.replace(/paged=[0-9]?/, 'paged='+ pageNum);

However, I think there should be better methods to parse and re-assemble URLs in Javascript.

answered Nov 3, 2012 at 17:22

Martin Ender

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Clyde Lobo · Accepted Answer · 2012-11-03 17:28:48Z

0

Here is a solution without using regex.

var url ="myurl.com/?page_id=2&paged=2" , pageNum=3;
url = url.split("paged=")[0]+"paged="+pageNum;

DEMO

answered Nov 3, 2012 at 17:28

Clyde Lobo

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