如何在 javascript 中使用正则表达式替换字符串？

Question

How to check a string and replace the space into "_"?

let str = "hello @%123abc456:nokibul amin mezba jomadder% @%123abc456:nokibul% @%123abc456:nokibul amin mezba%"

str = str.replace(regex, 'something');

console.log(str);

// Output: str = "hello @%123abc456:nokibul_amin_mezba_jomadder% @%123abc456:nokibul% @%123abc456:nokibul_amin_mezba%"

Please help me out:)

Answer 1

Hint: You can use https://regex101.com/ to test whether a regex works, it supports substitution as well.

Regex being used: (\w+)[ ] , to grep all words between space, and use $1_ to substitute the space to underscore.

 const regex = /(\w+)[ ]/gm; const str = `Input: str="nokibul" output: str="nokibul" Input: str="nokibul amin" Output: str="nokibul_amin" Input: str="nokibul amin mezba" Output: str="nokibul_amin_mezba" Input: str="nokibul amin mezba jomadder" Output: str="nokibul_amin_mezba_jomadder"`; const subst = `$1_`; // The substituted value will be contained in the result variable const result = str.replace(regex, subst); console.log('Substitution result: ', result);

Answer 2

Check this out. I think it's gonna help
Hints:

1. /:(\w+\s*)+/g Separates the :nokibul amin mezba jomadder as a group.
2. Replace the group with index-wise templating {0} , {1} ... {n} .
3. Mapping the groups. Ex: :nokibul amin mezba jomadder to :nokibul_amin_mezba_jomadder .
4. Finally, replacing the templates {index} with groups.

 let str = "hello @%123abc456:nokibul amin mezba jomadder% @%123abc456:nokibul% @%123abc456:nokibul amin mezba%"; /* Extracting Groups */ let groups = str.match(/:(\w+\s*)+/g); /* Formatting Groups: Replacing Whitespaces with _ */ let userTags = groups.map((tag, index) => { /* Index wise string templating */ str = str.replace(tag, `{${index}}`) return tag.replace(/\s+/g, "_"); }); console.log(str); console.log(userTags); /* Replacing string templates with group values */ userTags.forEach((tag, index) => str = str.replace(`{${index}}`, tag)); console.log(str);

Answer 3

Simple one liner

str.replace(/:[^%]*%/g, arg => arg.replace(/ /g, '_'))

Explanation:

/:[^%]*%/g Find all occurrences starting with : and ending at %

This will return patterns like this :nokibul amin mezba jomadder% :nokibul% :nokibul amin mezba%

Next is to replace all space characters with underscores using this replace(/ /g, '_')