Question

i have: \£\d+\.\d\d

should find: £6.95 £16.95 etc
+ is one or more
\. is the dot
\d is for a digit

am i wrong? 🙁

---

JavaScript for Greasemonkey

// ==UserScript==
// @name           CurConvertor
// @namespace      CurConvertor
// @description    noam smadja
// @include        http://www.zavvi.com/*
// ==/UserScript==
textNodes = document.evaluate(
                              "//text()",
                              document,
                              null,
                              XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
                              null);
var searchRE = /\£[0-9]\+.[0-9][0-9];
var replace = 'pling';
for (var i=0;i<textNodes.snapshotLength;i++) {
    var node = textNodes.snapshotItem(i);
    node.data = node.data.replace(searchRE, replace);
}

when i change the regex to /Free for example it finds and changes. but i guess i am missing something!

Answer 1

Had this written up for your last question just before it was deleted.

Here are the problems you’re having with your GM script.

1. You’re checking absolutely every
   text node on the page for some
   reason. This isn’t causing it to
   break but it’s unnecessary and slow.
   It would be better to look for text
   nodes inside .price nodes and .rrp
   .strike nodes instead.

2. When creating new regexp objects in
   this way, backslashes must be
   escaped, ex:

   var searchRE = new
   RegExp(‘\\d\\d’,’gi’);

   not

   var
   searchRE = new RegExp(‘\d\d’,’gi’);

   So you can add the backslashes, or
   create your regex like this:

   var
   searchRE = /\d\d/gi;

3. Your actual regular expression is
   only checking for numbers like
   ##ANYCHARACTER##, and will ignore £5.00 and £128.24

4. Your replacement needs to be either
   a string or a callback function, not
   a regular expression object.

---

Putting it all together

textNodes = document.evaluate(
                              "//p[contains(@class,'price')]/text() | //p[contains(@class,'rrp')]/span[contains(@class,'strike')]/text()",
                              document,
                              null,
                              XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
                              null);
var searchRE = /£(\d+\.\d\d)/gi;
var replace = function(str,p1){return "₪" + ( (p1*5.67).toFixed(2) );}

for (var i=0,l=textNodes.snapshotLength;i<l;i++) {
    var node = textNodes.snapshotItem(i);
    node.data = node.data.replace(searchRE, replace);
}

Changes:

• Xpath now includes only p.price and p.rrp span.strke nodes
• Search regular expression created with /regex/ instead of new RegExp
• Search variable now includes target currency symbol
• Replace variable is now a function that replaces the currency symbol with a new symbol, and multiplies the first matched substring with substring * 5.67
• for loop sets a variable to the snapshot length at the beginning of the loop, instead of checking textNodes.snapshotLength at the beginning of every loop.

Hope that helps!

[edit]Some of these points don’t apply, as the original question changed a few times, but the final script is relevant, and the points may still be of interest to you for why your script was failing originally.