如何使用javascript在以下情况下编写正则表达式？

Question

var value = "ID=advIcon1&CLASS=advIcon&PAGE=43&TOP=2%&LEFT=15%&WIDTH=20%&HEIGHT=10%&RSC=http://www.canon.com.hk/40th/index.html?source=seriesbanner&ICON=http://203.80.1.28/FlippingBook/Dev/Frontend/source/adv/tc_bn_314.jpg&ALT=Cannon Adv"

What I would like to achieve is from

&RSC=http://www.canon.com.hk/40th/index.html?source=seriesbanner

to

&RSC=http://www.canon.com.hk/40th/index.html?source#seriesbanner

which replace all the "=" between &RSC and &ICON

value = value.replace (/&RSC=%[=]+%&ICON/,/&RSC=%[#]+%&ICON/); 

The above is the code I tried, not working though, how to fix the problem ? thanks

Answer 1

I would do it like this:

var value = "ID=advIcon1&CLASS=advIcon&PAGE=43&TO...";
var startIndex = value.indexOf("&RSC");
var endIndex = value.indexOf("&ICON");
var head = value.substring(0, startIndex);
var tail = value.substring(endIndex);
var body = value.substring(startIndex, endIndex);
var result = head + body.replace(/=/g, '#') + tail;

I don't see any advantage in trying to do the whole thing with one crazy regex.

That will only make your code harder to read and less efficient.

Better yet, make it a function you can re-use:

// Replaces every occurrence of replaceThis with withThis in input between
// startPattern and endPattern.

function replaceCharactersBetween(input, startPattern, endPattern, replaceThis, withThis) {
    var startIndex = input.indexOf("startPattern");
    var endIndex = input.indexOf("endPattern");
    var head = input.substring(0, startIndex);
    var tail = input.substring(endIndex);
    var body = input.substring(startIndex, endIndex);
    var regex = new RegExp(replaceThis, 'g');
    return head + body.replace(regex, withThis) + tail;
}

Answer 2

Try:

value = value.replace(/RSC=([^=]+)=([^=]+)/, 'RSC=$1#$2');

You should look at endoceURIComponent() as well.