All Tools VerseJavaScript strings come with methods for searching, slicing, transforming, and converting text. This cheat sheet groups the methods you use most, and notes that strings are immutable so each one returns a new value.
Search and test
| Method | What it does |
|---|---|
includes(s) |
True if the substring is present |
startsWith(s) / endsWith(s) |
True if the string starts or ends with the text |
indexOf(s) |
Position of a substring, or -1 |
lastIndexOf(s) |
Position of a substring, searching from the end |
at(i) |
Character at an index; supports negatives, e.g. at(-1) |
charAt(i) |
Character at an index |
match(re) / matchAll(re) |
Find matches for a regular expression |
search(re) |
Index of the first regular-expression match |
Extract and split
| Method | What it does |
|---|---|
slice(start, end) |
Copy a section; supports negative indexes |
substring(start, end) |
Copy the text between two indexes |
substr(start, len) |
Copy a length of text from a start (legacy) |
split(sep) |
Split the string into an array on a separator |
Transform
| Method | What it does |
|---|---|
toUpperCase() / toLowerCase() |
Change the case of the string |
trim() |
Remove whitespace from both ends |
trimStart() / trimEnd() |
Remove whitespace from one end |
padStart(n, s) / padEnd(n, s) |
Pad to a length with a fill string |
repeat(n) |
Repeat the string n times |
replace(a, b) |
Replace the first match (or all with a global regex) |
replaceAll(a, b) |
Replace every match |
normalize() |
Normalize the Unicode form of the string |
Build and convert
| Method | What it does |
|---|---|
String(x) |
Convert any value to a string |
`Hi ${name}` |
Template literal: embed values inside backticks |
JSON.stringify(x) |
Convert a value to JSON text |
Number(s) / parseInt(s) |
Convert text to a number |
s.length |
The number of code units in the string |
Frequently Asked Questions
Are JavaScript strings mutable?
No. Strings are immutable, so any method that appears to change a string actually returns a new string and leaves the original alone.
What is the difference between slice and substring?
Both copy part of a string. slice accepts negative indexes counting from the end. substring treats negatives as 0 and swaps the two arguments if they are out of order.
How do I replace all occurrences of text?
Use replaceAll(a, b), or replace with a global regular expression such as /x/g. Plain replace changes only the first match.
How do I check whether a string contains text?
Use includes(text), which returns true or false. Use indexOf(text) when you also need the position of the match.
Pair this with our developer and text tools for encoding, formatting, and more.