How to replace a string with a number with another string number

Question

I have a string that contains a value that looks like this.

somevalueshere=123&page=3&someothervalues=123

and I want to replace the number 3 with 1. So it would look like page=1

The number is always a positive whole number like 1,2,3,4,5,6,7

All I have so far is

.replace("page=" + 'some number reg ex here', "page=1")

Possible duplicate of Using javascript replace to replace numbers in a string? — Heretic Monkey
– Heretic Monkey, Commented Jan 11, 2017 at 22:41
@MikeMcCaughan That doesn't look for a pattern before the number, it just replaces the number anywhere. — Barmar
– Barmar, Commented Jan 11, 2017 at 22:51
So, the question is, do we want users to have to think or not? Or learn regex rather than coming back to SO every time? Apparently not. How about stackoverflow.com/q/1090948/215552? That will let them change any part of the query string they want. — Heretic Monkey
– Heretic Monkey, Commented Jan 11, 2017 at 23:08

Barmar · Accepted Answer · 2017-01-11 22:39:53Z

3

The regular expression for a number (without decimals) is \d+. \d matches any numeric digit, and + means at least one of the preceding pattern.

str = str.replace(/\bpage=\d+/, 'page=1');

This is very basic regular expression syntax. If you don't already know it, you should read the tutorial at http://www.regular-expression.info.

answered Jan 11, 2017 at 22:38

Barmar

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7 Comments

Could you please explain the regex before I upvote it

@Barmar, really? You couldn't find a dupe for this? Do you really need more rep? :P

@MikeMcCaughan Sometimes it's easier to write a simple answer than go searching for things like this. The search terms tend to be too generic.

@MikeMcCaughan This isn't a generic forum. Please take your salt elsewhere

@CarlMarkham This isn't a help site. We're compiling a library of high-quality questions and answers, not collection of duplicate questions.

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