Navigating through the text in between search restrictions of lookbehind and lookahead can be

Question

Navigating through the text in between search restrictions of lookbehind and lookahead can be

Below is the text I am working with.

Hello my name is Adam (age: 25) I live in US.

Hello my name is Bill (age: 23) I live in Asia.

I am trying to extract the age and location using lookahead and lookbehind.

The desired output format should be as follows.

["25, US", "23, Asia"]

This is how much progress I have made so far.

(?<=age: ).*?(?=$)

When using the JavaScript match function, I am getting this array.

["25) I live in US.", "23) I live in Asia."]

I tried replacing .*? with [0-9a-zA-Z] but it doesn't seem to be effective.

javascript regex

Answer 1

Answer №1

Perhaps,

.*\bage:\s*(\d+)\s*\) I reside in (.+)\.

might be a bit closer, with two capturing groups containing your desired strings.

Test

const regex = /.*\bage:\s*(\d+)\s*\) I reside in (.+)\./gm;
const str = `Hello my name is Adam (age: 25) I reside in US.
Hello my name is Bill (age: 23) I reside in Asia.`;
const subst = `$1, $2`;

const result = str.replace(regex, subst);

console.log(result);

If you want to simplify/update/experiment with the expression, it has been detailed on the top right panel of regex101.com. You can observe the matching steps or make changes in this debugger link, if you're interested. The debugger illustrates how a RegEx engine would sequentially process some sample input strings for matching.

RegEx Circuit

jex.im visualizes regular expressions:

https://i.sstatic.net/MdZJq.png

Answer 2

Perhaps,

.*\bage:\s*(\d+)\s*\) I reside in (.+)\.

might be a bit closer, with two capturing groups containing your desired strings.

Test

const regex = /.*\bage:\s*(\d+)\s*\) I reside in (.+)\./gm;
const str = `Hello my name is Adam (age: 25) I reside in US.
Hello my name is Bill (age: 23) I reside in Asia.`;
const subst = `$1, $2`;

const result = str.replace(regex, subst);

console.log(result);

If you want to simplify/update/experiment with the expression, it has been detailed on the top right panel of regex101.com. You can observe the matching steps or make changes in this debugger link, if you're interested. The debugger illustrates how a RegEx engine would sequentially process some sample input strings for matching.

RegEx Circuit

jex.im visualizes regular expressions:

https://i.sstatic.net/MdZJq.png

Answer 3

Answer №2

The request for your query was to use lookbehind and lookahead in the regex. However, in this scenario, utilizing them is not really necessary since it has been noted that some browsers may not support lookbehind. But just to showcase how it would appear, I have provided it below:

/^.*?(?<=age: )(\d+).*?(?<=I live in )([^.]+)(?=\.$).*?$/gm

^ denotes the start of the line.
.*? finds the minimum match of 0 or more characters until:
(?<=age: )(\d+) locates 1 or more digits that are preceded by 'age: ' (you can adjust this to (?<=age: +) to allow multiple spaces before the number).
.*? seeks the minimal match of 0 or more characters until:
(?<=I live in )([^.]+)(?=\.$) matches 1 or more non-period characters that come after the string 'I live in ' and before a period at the end of the line.
.*?$ encompasses the remaining characters until the end of the line (which will just be a period).

let s = `Hello my name is Adam (age: 25) I live in US.

Hello my name is Bill (age: 23) I live in Asia.`;

let regex = /^.*?(?<=age: )(\d+).*?(?<=I live in )([^.]+)(?=\.$).*?$/gm;
let result = s.replace(regex, `$1, $2`);
console.log(result);

Answer 4

The request for your query was to use lookbehind and lookahead in the regex. However, in this scenario, utilizing them is not really necessary since it has been noted that some browsers may not support lookbehind. But just to showcase how it would appear, I have provided it below:

/^.*?(?<=age: )(\d+).*?(?<=I live in )([^.]+)(?=\.$).*?$/gm

^ denotes the start of the line.
.*? finds the minimum match of 0 or more characters until:
(?<=age: )(\d+) locates 1 or more digits that are preceded by 'age: ' (you can adjust this to (?<=age: +) to allow multiple spaces before the number).
.*? seeks the minimal match of 0 or more characters until:
(?<=I live in )([^.]+)(?=\.$) matches 1 or more non-period characters that come after the string 'I live in ' and before a period at the end of the line.
.*?$ encompasses the remaining characters until the end of the line (which will just be a period).

let s = `Hello my name is Adam (age: 25) I live in US.

Hello my name is Bill (age: 23) I live in Asia.`;

let regex = /^.*?(?<=age: )(\d+).*?(?<=I live in )([^.]+)(?=\.$).*?$/gm;
let result = s.replace(regex, `$1, $2`);
console.log(result);

Navigating through the text in between search restrictions of lookbehind and lookahead can be

Answer №1

Test

RegEx Circuit

Answer №2

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