Replace dynamic string value using javascript

Question

Here's the question: How can I replace a value in a string that can vary? I'm guessing you need to use a regex..

Here's what i'm trying to do:

  var height = 500;

  var urlstr = "...?height=300&width=200";

  var newurl = urlstr.replace("height=%&","height="+height+"&");

  alert(newurl);

Notice that I'm currently trying to account for the dynamic value using a "%" sign, however this doesn't work.. I'm not great at using regex and would be grateful if any of you could give me a hint, or alternately tell me if I'm approaching this wrongly ;)

Blender · Accepted Answer · 2012-06-07 03:23:04Z

3

Yep, you'll need regex. Fortunately it isn't very complicated:

var height = 500;
var urlstr = "...?height=300&width=200";
var newurl = urlstr.replace(/(height=)([0-9]+)/, '$1' + height);

alert(newurl);

answered Jun 7, 2012 at 3:23

Blender

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3 Comments

user1199434 Over a year ago

Thanks that worked perfectly, if you don't mind me asking, what does this bit do '$1' ? I'm a little bit confused by that part.. PS blender rules :)

Blender Over a year ago

$1 refers to the first matched group, which is height=. I was lazy and didn't want to write out height= so I matched it with $1 instead. $2 holds the contents of the old height, just in case you'll ever need it.

Blender Over a year ago

And yes, Blender rules ;) It's awesome.

user1419950 · Accepted Answer · 2012-06-07 03:26:41Z

2

"%" will be urlencoded "%25".
for your ref,
javascript encodeURIComponent

answered Jun 7, 2012 at 3:26

user1419950

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