Problems porting python regex to JS

**leke** · 05-20-2012 05:27 PM

Hi, I tried to port some python regex to JS, but the results were unexected

Code:

text = "[start 0.0]one one[end 5.25]this should not display[start 9]two two.[end 18.5][start 30]three three[end 50]";
document.write(text + "<br/ ><br/ >");

// define regex
starts = /\[start\s([\d\.]+)\]/g;
document.write(text.match(starts) + "<br/ ><br/ >");

words = /\[start\s[\d\.]+\](.*?)\[end\s[\d\.]+\]/g;
document.write(text.match(words) + "<br/ ><br/ >");

ends = /\[end\s([\d\.]+)\]/g;
document.write(text.match(ends) + "<br/ ><br/ >");

Which returns...

Code:

[start 0.0]one one[end 5.25]this should not display[start 9]two two.[end 18.5][start 30]three three[end 50]

[start 0.0],[start 9],[start 30]

[start 0.0]one one[end 5.25],[start 9]two two.[end 18.5],[start 30]three three[end 50]

[end 5.25],[end 18.5],[end 50]

Here is the python, which returns what I expected...

Code:

s = '\[start\s([\d\.]+)\]'
start = re.findall(s, text)

# Start and end times for each word
e = '\[end\s([\d\.]+)\]'
end = re.findall(e, text)

# this will get you the word you need to display.
w = '\[start\s[\d\.]+\](.*?)\[end\s[\d\.]+\]'
words = re.findall(w, text)

returns...

Code:

>>> start
['3.3', '8', '16']
>>> end
['6', '13', '20']
>>> words
['one one', 'two two.', 'three three']

Anyone know why this is?
Thanks.

**007Julien** · 05-21-2012 09:35 AM

The match() method searches a string for a match against a regular expression, and returns the matches, as an Array object (w3cschools.com). Then you should write something like this :

Code:

text = "[start 0.0]one one[end 5.25]this should not display[start 9]two two.[end 18.5][start 30]three three[end 50]";
document.write(text + "<br/ ><br/ >");

startReg= /\[start\s([\d\.]+)\]/g;
starts=text.match(startReg);
for (i=0;i<starts.length;i++)document.write(starts[i]+",  ");
document.write("<br/ ><br/ >");

It would still be advisable to remove the brackets and the word start... Then the replace method with a function will be more effective, with only one regular expression (do not use document write, which is only valid for an opening document).

Code:

<body>
<div id="pge"></div>
<script type="text/javascript">
text = "[start 0.0]one one[end 5.25]this should not display[start 9]two two.[end 18.5][start 30]three three[end 50]";
// The document is existing at the end of the body
document.getElementById('pge').innerHTML=text + "<br>";

// We use a replace method only to define new variables
var start=end=word=''; 
text.replace(/\[start\s([\d\.]+)\]([^\[]+)\[end\s([\d\.]+)\]/g,
		function(allMatch,firstSubPat,secondSubPat,thirdSubPat){
		   start+=', '+firstSubPat;
		   word+=', '+secondSubPat;
		   end+=', '+thirdSubPat;
		});
document.getElementById('pge').innerHTML+='start : '+start.substr(2)+'<br>&nbsp;end : '+end.substr(2)+'<br>word : '+word.substr(2);		
</script>
</body>

Obviously start, word and end could be arrays...

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