JavaScript replace() and replaceAll()

Use replace() to replace the first string match (or matches selected by a regular expression). Use replaceAll() when you want every occurrence of a fixed string replaced.

const text = "PHP tutorial and PHP examples";
const updated = text.replace("PHP", "JavaScript");
console.log(updated); // JavaScript tutorial and PHP examples

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replace() syntax Top ↑

string.replace(pattern, replacement)

The original string is not mutated.

Replace the first string match Top ↑

const text = "PHP tutorial and PHP examples";
console.log(text.replace("PHP", "JavaScript"));

Replace all occurrences Top ↑

const text = "PHP tutorial and PHP examples";
console.log(text.replaceAll("PHP", "JavaScript"));

replaceAll() is the clearest choice for every occurrence of a literal string.

Global replacement with a regular expression Top ↑

const text = "PHP tutorial and PHP examples";
console.log(text.replace(/PHP/g, "JavaScript"));

Case-insensitive replacement Top ↑

const text = "PHP tutorial and php examples";
console.log(text.replace(/php/gi, "JavaScript"));

The i flag ignores case and g selects all matches.

Replacement function Top ↑

const text = "Price: 20, tax: 5";
const result = text.replace(/\d+/g, value => String(Number(value) * 2));
console.log(result); // Price: 40, tax: 10

A replacer function can calculate replacement text dynamically.

Use capture groups in replacement text Top ↑

const name = "Mohapatra Subhendu";
console.log(name.replace(/(\w+) (\w+)/, "$2 $1"));

Common mistakes Top ↑

A plain string passed to replace() changes only the first occurrence. If you pass a regular expression to replaceAll(), it must use the global g flag. See also string searching.

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Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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