javascript string.replace against negative list

Question

I know it's preferable to use a whitelist when dealing with regexp, but due to client requirement I can't do that. They don't want us to prevent the user from entering special characters - we need to allow them to enter them, and then strip them out before saving.

So say I have something like this:

$('#clickMe').click(function() {
    var test = $('#pizza').val();
    var pattern = /[a-z][0-9]/;
    if (!pattern.test(test)) {
        console.log("not pass: " + test);
    }
    else {
        console.log("passes");
    }
})

How can I do a string.replace() and replace any characters in test that aren't in the pattern?

ETA: here's a fiddle; if you enter something like Esther (test*&^) pizza in the input field, I want it to return Esther test pizza.

anubhava · Accepted Answer · 2013-08-02 17:19:47Z

2

Define your regex like this:

var test = $('#pizza').val();
var pattern = /[^\w\s]+/g;
if (pattern.test(test)) {
    console.log("not pass: " + test);
    var cleanVal = test.replace(pattern, '');   
    // set cleanVal to wherever you want
    $('#pizza').val(cleanVal);
}
else {
    console.log("passes");
}

answered Aug 2, 2013 at 17:19

anubhava

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Logan Murphy · Accepted Answer · 2013-08-02 17:13:57Z

0

If you wanted to remove the unwanted characters

var test = test.replace(/[^a-z0-9]/gi, ""); //g means all, i means case insensitve

answered Aug 2, 2013 at 17:13

Logan Murphy

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Comments

Denys Séguret · Accepted Answer · 2013-08-02 17:17:07Z

0

I think the correct pattern is /[a-z0-9]/, not /[a-z][0-9]/.

The best solution would involve changing a little the expression :

var cleanString = test.replace(/[^a-z0-9]/g,'');

If you can't, then you can do this :

var cleanString = test.match(/[a-z0-9]/g).join('');

edited Aug 2, 2013 at 17:17

answered Aug 2, 2013 at 17:11

Denys Séguret

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4 Comments

EmmyS Over a year ago

I tried /[a-z0-9]/, and it allowed 123@ and 1@23 to pass.

Denys Séguret Over a year ago

You mean if you use the test function ? In that function you must make the regex cover the whole string : /^[a-z0-9]*$/

Justin Morgan Over a year ago

This will fail on capital letters.

Denys Séguret Over a year ago

@JustinMorgan That's the pattern of the question.

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