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regular expression in Javascript

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May 26.2013

In code that I am reading I have the following regular expression:

[CODE]‘([0-9]*)x([0-9]*)’[/CODE]

and for the code:

[CODE]“400×300”[/CODE]

It give me the following array:

[CODE][400×300,400,300][/CODE]

I understand why the first element in the array, 400×300, but how come the last two match the regular expression?

They don’t have the x.

Can someone please explain to me why the last 2 element match the regular expression.

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JavaScript

3 Comments(s) ↴

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@iBeZiMay 26.2013 — The two areas enclosed in brackets tell the regular expression that you want to "capture" whatever appears inside the brackets.

So the regular expression matches "400x300" as a whole, but then gives you the two numbers separately because they are enclosed in brackets.
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@programAngelauthorMay 27.2013 — iBeZi, thank you.
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@wbportMay 28.2013 — Putting parenthesis "()" around part of a regular expression is a way to determine it's value and take appropriate action. For example, in the text based music notation system [B]abc[/B], the following examines a note:[CODE]
 // <stc><-- accidental----><--note--><octav><num>< / ><dem><trail>
var anote = /(.?)(^{0,2}|=?|_{0,2})([A-Ga-g])([',]*)(d*)(/*)(d*)([- ]*)/;[/CODE]
Only the upper or lower case letters "a-g" have to be there-- a stacatto dot, an accidental, octave change, duration, and/or trailing dash or space are all optional. This is an example of some code that follows a [B]match[/B] command: [CODE]
 for (var i =0; i<result[4].length; i++) {
var achar = result[4].charCodeAt(i); // alert("achar = " + achar);
if (achar == 44) {pos -= 7;} // Comma down
if (achar == 39) {pos += 7;} } //Apostrophe, up[/CODE]

HTH
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