JS REGEX 07: Match, Replace, Split, and Search
Regular Expressions (RegExp) are patterns used to match character combinations in strings. JavaScript provides helpful string methods that accept RegExp as input to find, replace, split, or search inside strings.
In this lesson, we’ll learn how to use:
match()replace()split()search()
Let’s go!
🧪 1. match() – Find patterns in a string
console.log("string".match(/[i-n]+/)); // → ["in"]
[i-n]means: match any letter from i to n.+means: match one or more of those letters."string"contains"in"→ so it returns["in"].
You can also capture part of the match:
console.log("string".match(/(r)[i-n]+/)); // → ["rin", "r"]
(r)is a capturing group.-
The result includes:
"rin"(the full match)"r"(the captured part)
🛠️ 2. replace() – Replace pattern with something else
console.log("string".replace(/[i-n]+/, "foo")); // → strfoog
[i-n]+matches"in""in"is replaced with"foo"- So
"string"becomes"strfoog"
✂️ 3. split() – Split string by the match
console.log("stringstring".split(/[i-n]+/)); // → ["str", "gstr", "g"]
- Splits the string wherever it finds letters from i to n.
"stringstring"→ split at"in"and"in"again- You get the array:
["str", "gstr", "g"]
🔍 4. search() – Find index of the match
console.log("string".search(/[i-n]+/)); // → 3
console.log("string".search(/[o-q]+/)); // → -1
- First one finds
"in"starting at index 3 - Second one finds nothing, so it returns
-1
📌 Summary Table
| Method | What it does |
|---|---|
match() |
Finds and returns matching content |
replace() |
Replaces matched content with new text |
split() |
Splits string by matched pattern |
search() |
Returns index of the first match or -1 |
🧠 Practice Time!
Try these on your own:
1️⃣ What does this return?
"banana".match(/[a-c]+/)
2️⃣ Replace all letters from d to f in "default" with "X".
3️⃣ What’s the result of:
"hellohello".split(/[l]+/)
4️⃣ Use .search() to find the position of "oo" in "school" using RegExp.
5️⃣ Use .match() with a capturing group to extract "cat" from "blackcat".
📬 Contact Me
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