Dynamic Replace In Regular Expression Scope

I need to rewrite some require paths in JavaScript source files: Example (foo => ../../../foo/baz): var a = require('foo/a'); => var b = require('../../../foo/baz/a'); var a

Solution 1:

I think this does it:

str = str.replace(/require\((['"])([^'"]*)foo\/([^'"]*)(['"])/g, "require($1$2../../../foo/baz/$3$4");

Here's that regex live: http://regex101.com/r/bE5jI4

Explanation:

• require matches the characters require literally (case sensitive)

• \( matches the character ( literally

• 1st Capturing group (['"])

  • ['"] match either ' or " literally

• 2nd Capturing group ([^'"]*)

  • [^'"]* match a single character not present in the list below

    • Quantifier: Between zero and unlimited times, as many times as possible, giving back as needed [greedy]

  • '" a single character in the list '" literally

• foo matches the characters foo literally (case sensitive)

• \/ matches the character / literally

• 3rd Capturing group ([^'"]*)

  • [^'"]* match a single character not present in the list below

    • Quantifier: Between zero and unlimited times, as many times as possible, giving back as needed [greedy]

    • '" a single character in the list '" literally

• 4th Capturing group (['"])

  • ['"] match ' or " literally

You may have to tweak it if there's optional whitespace before the opening quotes, or if your paths may contain ' or " characters. (In that latter case, you'll need two replacements, one when the wrapper quotes are ' and the other when they're ".)

Solution 2:

This should work:

var source = '';
source += "var a = require('foo/a');\n";
source += "var b = require('foo/../b');\n";
source += "console.log(a + b);";

var options = {
  'foo': '../../../foo/baz'
};

for (var key in options) {
  var regex = new RegExp('(require)\\((["\'])(' + key + ')([^"\']*)\\2\\)', 'g');
  source = source.replace(regex, "$1('" + options[key] + "$4')");
}
console.log(source);

OUTPUT:

var a = require('../../../foo/baz/a');
var b = require('../../../foo/baz/../b');
console.log(a + b);