JavaScript/node.js convert array into regex.match arguments for if statement

Question

I have written a node module with several places that use regular expressions to limit which files are manipulated as below:

if (!file.match(/\/node_modules\//) && !file.match(/\/fontawesome\//) && !file.match(/\/docs\//) && !file.match(/\/target\//) && !seenFile[file]) {
    //do some processing
}

I'm trying to modify the module to accept user input as an array - i.e.:

['/node_modules/', '/fontawesome/', '/docs/', '/target/']

Is there a good way to convert the array into the regex? I know apply might work if I wasn't using file.match but I'm not sure if it will work in this instance. Thanks in advance.

Just trying to figure out what you need: is this code of any help? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Nov 2, 2015 at 20:51
Thanks, that was a big help. I was confused about || in js vs. | in regex. — user4479529
– user4479529, Commented Nov 2, 2015 at 21:52
So, can I post it as an answer? I think there is one mistake: RegExp(rx) must be used. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Nov 2, 2015 at 21:53

Wiktor Stribiżew · Accepted Answer · 2015-11-02 21:57:33Z

1

You can use the array of values to build a dynamic regex:

Escape all special regex characters with .replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
Build the regex with the help of | alternation operator
Use the regex with String#match or RegExp#exec methods.

Here is a working snippet:

var ar = ['/node_modules/', '/fontawesome/', '/docs/', '/target/'];
ar = ar.map(function(item) {  
          return item.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
       });
var rx = RegExp(ar.join("|"));

var file = "/node_modules/d.jpg";
if (!file.match(rx)) {
    console.log("No stop words found!");
} else {
    console.log("Stop words found!");
}

answered Nov 2, 2015 at 21:57

Wiktor Stribiżew

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