var regEx = new RegExp("/[0-9]/");
var test = 'TREE'
alert(test.match(regEx));

or

var regEx = new RegExp("/[0-9]/");
var test = '1234'
alert(test.match(regEx));

Why do they return null?

Am i missing something here?

(Ok, the debate mentally drained me last night)

var regEx = new RegExp("/[0-9]/");
var test = 'TREE'
alert(test.match(regEx));

or

var regEx = new RegExp("/[0-9]/");
var test = '1234'
alert(test.match(regEx));

Why do they return null?

Am i missing something here?

(Ok, the debate mentally drained me last night)

• javascript

Share Improve this question Follow edited Oct 17, 2012 at 14:48 Alex K. 176k3232 gold badges274274 silver badges296296 bronze badges asked Oct 17, 2012 at 14:42 PinchPinch 4,20788 gold badges4242 silver badges6161 bronze badges

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2 Answers 2

Sorted by: Reset to default 6

When you are using new RegExp, you don't need the delimiters (/).

var regEx = new RegExp("[0-9]");
var test = '1234'
alert(test.match(regEx));

You only need the slashes if you are using a regex literal (which I prefer using to new RegExp).

var regEx = /[0-9]/;
var test = '1234'
alert(test.match(regEx));

To declare a RegExp:

var patt=new RegExp(pattern,modifiers); 

or

var patt=/pattern/modifiers;

So try this:

var regEx = /[0-9]/g;
var test = '1234';
alert(test.match(regEx));