PHP regular expressions to Javascript within if statements

Question

I understand how to use the regular expressions in JS and PHP. I'm trying to switch some of my PHP code to JS and I have a function that goes through different regular expressions to see if it can find a match.

Example PHP:

if(preg_match('/regex1/', $string, $matches)) { 
    $output = $matches[1]; 
} else if(preg_match('/regex2/', $string, $matches)) {
    $output = $matches[1];
} else etc....

Is there a way to do something similar in JS?

The only way I can think of doing it is:

if(string.match(/regex/)) {
   var res = string.match(/regex/);
   output = res[1];
} else if ..... and so on

I'd rather not have it do the match twice... Is there another way?

Thanks for your help.

Jonathan M · Accepted Answer · 2015-05-13 20:47:35Z

1

You could do:

var res;
if(res = string.match(/regex/)) {
   output = res[0];
} else if ..... and so on

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/match

edited May 13, 2015 at 20:47

answered May 13, 2015 at 20:36

Jonathan M

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2 Comments

tathyler Over a year ago

This is great. Just test it with: if(res = string.match(/regex/)) and seems to work fine. Any reason to keep the "!== null" since the condition already checks that?

Jonathan M Over a year ago

@tathyler, no, since even an empty array or array with a single falsey element is going to return a truthy value.

maxisme · Accepted Answer · 2015-05-13 20:43:53Z

0

You could build an array of regexs like this:

var array = ["/regex1/", "/regex2/", "/regex3/", "/regex4/"];
var x;
for (index = 0; index < array.length; ++index) {
    if(string.match(array[index]))){
        x++;
        output = matches[x]; 
    }
}

edited May 13, 2015 at 20:43

answered May 13, 2015 at 20:37

maxisme

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1 Comment

Jonathan M Over a year ago

He's wanting javascript.

mgerton · Accepted Answer · 2015-05-13 20:55:09Z

0

Take a look at MDN's docs on Regular expressions, specifically the available methods. I think what you want here is the exec method rather than match, as that will return an array of matched results, just like preg_match in PHP. You will likely need to store the result of the exec call first, and then in your conditions you should check for a length on the result.

var matches = mystring.exec(/regex1/);
var output;

if (matches.length) {
  output = matches[0];
}

edited May 13, 2015 at 20:55

answered May 13, 2015 at 20:45

mgerton

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