Incorporate a variable into a string

Question

Incorporate a variable into a string

My task here is to prepend a variable before each specific string in the given text.

For example:

var exampleString = "blabla:test abcde 123test:123";
var formattedString = "el.blabla:test abcde el.123test:123";

In this case, whenever there is a pattern like "XXX:XXX", I am required to add a variable before it.

I already have a regex pattern to identify "XXX:"

var regex = new RegExp(/\w+([aA-zZ]:)/g)

However, when attempting to replace it, all occurrences are replaced instead of just adding the variable "el."

var exampleString = "blabla:test abcde 123test:123";
var formattedString = exampleString.replace(new RegExp(/\w+([aA-zZ]:)/g), 'el.');
// The result should be "el.blabla:test abcde el.123test:123"
// But it returns "el.test abcde el.123"

Can someone help me make this work correctly? Thank you :)

Source: Javascript Regex: How to put a variable inside a regular expression?

javascript regex

Answer 1

Answer №1

let phrase = "testing example: 123 abcdefg testing:456";
let updatedPhrase = phrase.replace(/\w*:\w*/gi, 'result.$&');
console.log(updatedPhrase);

Explanation and demonstration of Regular Expression can be found here

Check out the working example on this JSFiddle link

Answer 2

let phrase = "testing example: 123 abcdefg testing:456";
let updatedPhrase = phrase.replace(/\w*:\w*/gi, 'result.$&');
console.log(updatedPhrase);

Explanation and demonstration of Regular Expression can be found here

Check out the working example on this JSFiddle link

Answer 3

Answer №2

To ensure a match only at the beginning, remember to use the symbol ^. Additionally, it's best to omit the g modifier if you only intend to replace once.

When creating regular expressions, opt for the simpler RegExp literal over new RegExp().

For the replacement string, utilize $& to retain the original text within the replacement.

var exampleString = "blabla:test abcde 123test:123";
var formattedString = exampleString.replace(/^\w+[a-z]:/i, 'el.$&');
console.log(formattedString);

It is recommended to specify all letters in any case using [A-Za-z], or employ the i modifier for case-insensitivity when matching. The current regex pattern matches characters ranging from A-z, encompassing unnecessary punctuation marks between uppercase and lowercase letters in the ASCII code.

Answer 4

To ensure a match only at the beginning, remember to use the symbol ^. Additionally, it's best to omit the g modifier if you only intend to replace once.

When creating regular expressions, opt for the simpler RegExp literal over new RegExp().

For the replacement string, utilize $& to retain the original text within the replacement.

var exampleString = "blabla:test abcde 123test:123";
var formattedString = exampleString.replace(/^\w+[a-z]:/i, 'el.$&');
console.log(formattedString);

It is recommended to specify all letters in any case using [A-Za-z], or employ the i modifier for case-insensitivity when matching. The current regex pattern matches characters ranging from A-z, encompassing unnecessary punctuation marks between uppercase and lowercase letters in the ASCII code.

Answer 5

Answer №3

Simply follow this

Use the following code snippet to manipulate strings:

Explanation of Regular Expression (REGEXP):

The parentheses (\w*) in the capturing group are used to capture any alphabet characters that occur any number of times. The $1 and $2 denote the first and second captured groups.

Answer 6

Simply follow this

Use the following code snippet to manipulate strings:

Explanation of Regular Expression (REGEXP):

The parentheses (\w*) in the capturing group are used to capture any alphabet characters that occur any number of times. The $1 and $2 denote the first and second captured groups.

Answer 7

Answer №4

Instead of using the replace function, consider implementing a custom function like insertAt. Here's an example to illustrate this:

String.prototype.insertAt=function(index, string) { 
  return this.substr(0, index) + string + this.substr(index);
}

var sampleText = "hello:world goodbye 123test:456";
var regexPattern = new RegExp(/\w+([aA-zZ]:)/g)
var modifiedText = sampleText;

while ( (result = regexPattern.exec(sampleText)) ) {
    modifiedText = modifiedText.insertAt(result.index, "!! ");
}

console.log(modifiedText);

I trust this explanation proves useful. Farewell!

Answer 8

Instead of using the replace function, consider implementing a custom function like insertAt. Here's an example to illustrate this:

String.prototype.insertAt=function(index, string) { 
  return this.substr(0, index) + string + this.substr(index);
}

var sampleText = "hello:world goodbye 123test:456";
var regexPattern = new RegExp(/\w+([aA-zZ]:)/g)
var modifiedText = sampleText;

while ( (result = regexPattern.exec(sampleText)) ) {
    modifiedText = modifiedText.insertAt(result.index, "!! ");
}

console.log(modifiedText);

I trust this explanation proves useful. Farewell!

Incorporate a variable into a string

Answer №1

Answer №2

Answer №3

Answer №4

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