Using Javascript regular expressions to substitute $1 with the result of f($1)

Question

Using Javascript regular expressions to substitute $1 with the result of f($1)

I need to update a regular expression, let's say it looks like this: /url.com\/([A-Za-z]+)\.html/. My goal is to replace it with new string $1: f($1), which involves a constant string with two interpolations - the captured string and a function of the captured string.

What is the optimal approach to achieve this in JavaScript? By 'optimal' I mean a method that is (1) the least error-prone, (2) the most efficient in terms of space and speed, and (3) the most idiomatically appropriate for JavaScript, placing a particular emphasis on #3.

javascript regex string idioms

Answer 1

Answer №1

The replace method has the capability to use a function as the replacement parameter. This can be seen in the example below:

For instance:

str.replace(/regex/, function(match, group1, group2, index, original) { 
    return "new string " + group1 + ": " + f(group1);
});

Answer 2

The replace method has the capability to use a function as the replacement parameter. This can be seen in the example below:

For instance:

str.replace(/regex/, function(match, group1, group2, index, original) { 
    return "new string " + group1 + ": " + f(group1);
});

Answer 3

Answer №2

When utilizing the String.replace method, you have the option to provide a callback function as the replacement parameter instead of a standard string. This allows you to generate a highly personalized return value.

'hello'.replace(/world/, function (match, group1, group2) {
    return /* insert your custom string here */;
});

Answer 4

When utilizing the String.replace method, you have the option to provide a callback function as the replacement parameter instead of a standard string. This allows you to generate a highly personalized return value.

'hello'.replace(/world/, function (match, group1, group2) {
    return /* insert your custom string here */;
});

Answer 5

Answer №3

.replace() allows you to use a function for the replacement, as shown below:

var modifiedString = originalString.replace(/example.com\/([A-Za-z]+)\.html/, function(all, matching) {
  return matching + " addition";
});

You have the freedom to manipulate the output as needed, simply dictate the desired replacement in the callback function. Give it a try here.

Answer 6

.replace() allows you to use a function for the replacement, as shown below:

var modifiedString = originalString.replace(/example.com\/([A-Za-z]+)\.html/, function(all, matching) {
  return matching + " addition";
});

You have the freedom to manipulate the output as needed, simply dictate the desired replacement in the callback function. Give it a try here.

Using Javascript regular expressions to substitute $1 with the result of f($1)

Answer №1

Answer №2

Answer №3

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