JavaScript String Methods
Index
About This Index
This page is the JavaScript String Methods index for the tutorial track. Each row links to a full guide with syntax, examples, and FAQs.
Learn what a String is on /js/string. Use this page when you need a specific API such as slice(), includes(), or trim().
Beginner path.
Start with slice(), includes(), trim(), and replace()—then browse the rest by category. HTML wrapper methods such as bold() are legacy; prefer document.createElement() in new code.
Syntax
How to Call a String Method
Instance methods use a dot; a few helpers use String:
JavaScript
const title = " JavaScript ";
// Instance (String.prototype)
title.trim(); // "JavaScript"
title.includes("Java"); // true
"Hello".slice(0, 2); // "He"
"a-b-c".split("-"); // ["a", "b", "c"]
// Static (on String)
String.fromCharCode(65); // "A"
String.fromCodePoint(128512); // "😀"Browse
JavaScript String Methods Table
All method guides in this JavaScript tutorial series (49 tutorials).
HTML Wrapper Methods (Deprecated)
13 methodsLegacy helpers that build HTML strings. Prefer document.createElement() in new code.
| Method | Description | Tutorial |
|---|---|---|
anchor() | Deprecated HTML wrapper: returns a string with <a name="..."> markup — prefer document.createElement(). | Open |
big() | Deprecated HTML wrapper: returns a string with <big> markup — prefer CSS font-size. | Open |
blink() | Deprecated HTML wrapper: returns a string with <blink> markup — avoid blinking text. | Open |
bold() | Deprecated HTML wrapper: returns a string with <b> markup — prefer createElement or CSS font-weight. | Open |
fixed() | Deprecated HTML wrapper: returns a string with <tt> markup — prefer CSS font-family: monospace. | Open |
fontcolor() | Deprecated HTML wrapper: returns a string with <font color="..."> markup — prefer CSS color. | Open |
fontsize() | Deprecated HTML wrapper: returns a string with <font size="..."> markup — prefer CSS font-size. | Open |
italics() | Deprecated HTML wrapper: returns a string with <i> markup — prefer createElement or CSS font-style. | Open |
link() | Deprecated HTML wrapper: returns a string with <a href="..."> markup — prefer document.createElement("a"). | Open |
small() | Deprecated HTML wrapper: returns a string with <small> markup — prefer createElement("small") or CSS font-size. | Open |
strike() | Deprecated HTML wrapper: returns a string with <strike> markup — prefer createElement("s") or createElement("del"). | Open |
sub() | Deprecated HTML wrapper: returns a string with <sub> markup — prefer document.createElement("sub"). | Open |
sup() | Deprecated HTML wrapper: returns a string with <sup> markup — prefer document.createElement("sup"). | Open |
Character Access
5 methodsRead characters, code units, code points, or iterate the string.
| Method | Description | Tutorial |
|---|---|---|
at() | Return the UTF-16 code unit at an index — supports negative offsets from the end (at(-1) is last). | Open |
charAt() | Return the UTF-16 code unit at a zero-based index — out of range returns "" (no negative indexes). | Open |
charCodeAt() | Return the UTF-16 code unit at an index as a number (0–65535) — out of range returns NaN. | Open |
codePointAt() | Return the full Unicode code point at a UTF-16 index — out of range returns undefined (handles emoji). | Open |
[Symbol.iterator]() | Make strings iterable by Unicode code points — powers for...of and spread; surrogate pairs stay together. | Open |
Search & Test
7 methodsFind substrings and test prefixes or suffixes.
| Method | Description | Tutorial |
|---|---|---|
includes() | Case-sensitive substring search that returns true or false — optional start position; regex not allowed. | Open |
indexOf() | Return the first index of a substring, or -1 if missing — optional start position; case-sensitive. | Open |
lastIndexOf() | Return the last index of a substring, or -1 if missing — optional from-position; case-sensitive. | Open |
startsWith() | Case-sensitive prefix check that returns true or false — optional position; regex throws TypeError. | Open |
search() | Return the index of the first regex match, or -1 — g flag has no effect; strings are coerced to RegExp. | Open |
match() | Match a string against a regular expression — returns an Array or null; g flag changes the result shape. | Open |
matchAll() | Iterate all regex matches with capturing groups — requires the g flag; returns an iterator. | Open |
Unicode & Well-Formed
3 methodsNormalize Unicode forms and detect or repair lone UTF-16 surrogates.
| Method | Description | Tutorial |
|---|---|---|
isWellFormed() | Return true if the string has no lone UTF-16 surrogates — useful before encodeURI(); pair with toWellFormed(). | Open |
toWellFormed() | Replace lone UTF-16 surrogates with U+FFFD (�) — safe for encodeURI(); pair with isWellFormed(). | Open |
normalize() | Return a Unicode Normalization Form (NFC/NFD/NFKC/NFKD) — default NFC; use before comparing lookalike text. | Open |
Extract & Split
4 methodsPull out parts of a string or split into arrays.
| Method | Description | Tutorial |
|---|---|---|
slice() | Extract a section into a new string — exclusive end index; negatives count from the end. | Open |
substring() | Extract between two indexes (exclusive end) — swaps if start > end; negatives treated as 0. | Open |
substr() | Legacy start+length extractor (deprecated Annex B) — prefer slice(); negative length returns "". | Open |
split() | Divide a string into an array by a string or regex separator — optional limit; capturing groups appear in the result. | Open |
Transform & Pad
9 methodsChange case, trim whitespace, pad, or repeat text.
| Method | Description | Tutorial |
|---|---|---|
toLowerCase() | Convert to lowercase with Unicode default mappings — great for case-insensitive compares; no locales arg. | Open |
toLocaleLowerCase() | Locale-aware lowercase — optional BCP 47 locales; Turkish İ differs from toLowerCase(). | Open |
toLocaleUpperCase() | Locale-aware uppercase — optional BCP 47 locales; Turkish i → İ; length may grow (ß → SS). | Open |
trim() | Remove whitespace from both ends — spaces, tabs, newlines; middle spaces kept; pair with trimStart/trimEnd. | Open |
trimStart() | Remove leading whitespace only — keeps trailing spaces; alias trimLeft(); pair with trim/trimEnd. | Open |
trimEnd() | Remove trailing whitespace only — keeps leading spaces; alias trimRight(); pair with trim/trimStart. | Open |
padStart() | Pad the start of a string to a target length — default space filler; great for zero-padding and masks. | Open |
padEnd() | Pad the end of a string to a target length — default space filler; padString repeats or truncates. | Open |
repeat() | Build a new string by concatenating the original count times — RangeError for negative or Infinity. | Open |
Combine & Replace
2 methodsJoin strings or swap matched text for new content.
| Method | Description | Tutorial |
|---|---|---|
replace() | Replace the first string match or regex matches — use g for all; support $ groups and replacer functions. | Open |
replaceAll() | Replace every string or global-regex match — TypeError if a RegExp is missing the g flag. | Open |
Compare & Convert
3 methodsSort-friendly comparison and primitive conversion.
| Method | Description | Tutorial |
|---|---|---|
localeCompare() | Locale-aware string ordering — returns <0 / 0 / >0; optional locales and options (sensitivity, numeric). | Open |
toString() | Return the string primitive — unwraps new String(...); same as valueOf(); TypeError for non-string this. | Open |
valueOf() | Return the string primitive — same as toString(); unwraps new String(...); usually called by the engine. | Open |
Static Methods
3 methodsHelpers on the String constructor — not called on an instance.
| Method | Description | Tutorial |
|---|---|---|
fromCharCode() | Static helper: build a string from UTF-16 code units (0–65535) — pair with charCodeAt(); prefer fromCodePoint() for emoji. | Open |
fromCodePoint() | Static helper: build a string from full Unicode code points (0–0x10FFFF) — emoji in one arg; invalid values throw RangeError. | Open |
raw() | Static template tag: keep escape sequences raw while still evaluating ${} — great for paths and RegExp sources. | Open |
Frequently Asked Questions
String methods are functions on String.prototype such as slice(), includes(), trim(), replace(), and split(). A few helpers are static and live on String itself: String.fromCharCode(), String.fromCodePoint(), and String.raw().
The String page teaches what a String is—quotes, template literals, immutability, and length. This Methods index lists every method tutorial so you can open slice(), includes(), trim(), and the rest.
Instance methods use a dot on a string: "Hello".slice(0, 2), " hi ".trim(), "JS".includes("J"). Static methods use String: String.fromCharCode(65).
No. Strings are immutable. Methods return a new string, a boolean, a number, or an array. Assign the result if you need to keep it.
If you are new, read JavaScript String first. Then open length on the properties index, and slice(), includes(), trim(), and replace() from the tables below.
Start with slice()
Open the extraction guide—syntax, examples, and FAQs.
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