JavaScript String repeat() Method

What You’ll Learn

String.prototype.repeat() builds a new string by concatenating the original text a given number of times (same API as MDN String.prototype.repeat()). Learn valid counts, RangeError cases, float truncation, separators and fillers, five examples, and try-it labs.

Introduction

Need the same text several times in a row — a divider line, a laugh ("ha" repeated, or a template phrase? repeat() concatenates copies of the string and returns one new result.

Pass how many copies you want as count. Zero copies give an empty string. Negative values or Infinity throw RangeError. Decimals are truncated to integers.

This page is part of JavaScript String Methods. Related topics include padStart() and padEnd().

Understanding the repeat() Method

str.repeat(count) returns a new string that contains str concatenated with itself count times.

• count should be a non-negative finite number.
• repeat(0) returns "".
• Floats are truncated (e.g. 3.9 → 3).
• Negative or infinite count throws RangeError.
• The original string is never modified.

📝 Syntax

General form of String.prototype.repeat:

str.repeat(count)

Parameters

• count — number of copies. Must be between 0 and a finite value that does not overflow maximum string length. Converted to an integer (truncated toward zero).

Return value

A string with count copies concatenated:

Common patterns

"abc".repeat(0);     // ""
"abc".repeat(1);     // "abc"
"abc".repeat(2);     // "abcabc"
"abc".repeat(3.5);   // "abcabcabc"

"ha".repeat(3);      // "hahaha"
"-".repeat(10);      // "----------"

`I feel ${"Happy! ".repeat(3)}`;
// "I feel Happy! Happy! Happy! "

Examples Gallery

Examples follow MDN String.repeat() patterns. Use View Output or Try It Yourself for each case.

const mood = "Happy! ";

`I feel ${mood.repeat(3)}`;
// "I feel Happy! Happy! Happy! "

I feel Happy! Happy! Happy! 

"abc".repeat(0);    // ""
"abc".repeat(1);    // "abc"
"abc".repeat(2);    // "abcabc"
"abc".repeat(3.5);  // "abcabcabc"  (truncated to 3)

abc
abcabc
abcabcabc

"-".repeat(20);
// "--------------------"

const indent = "  ".repeat(2);
indent + "nested item";
// "    nested item"

"*".repeat(5) + " STAR " + "*".repeat(5);
// "***** STAR *****"

--------------------
    nested item
***** STAR *****

"ha".repeat(3);
// "hahaha"  (no spaces)

Array(3).fill("ha").join(" ");
// "ha ha ha"

Array(4).fill("●").join("-");
// "●-●-●-●"

hahaha
ha ha ha
●-●-●-●

try {
  "abc".repeat(-1);
} catch (e) {
  e.name;  // "RangeError"
}

try {
  "abc".repeat(1 / 0);  // Infinity
} catch (e) {
  e.name;  // "RangeError"
}

// Generic method (works on other objects with toString):
({ toString: () => "abc", repeat: String.prototype.repeat }).repeat(2);
// "abcabc"

RangeError
RangeError
abcabc

🚀 Common Use Cases

• Divider / ruler lines — "-".repeat(40) in console or reports.
• Indentation — " ".repeat(level * 2) for tree-style logs.
• Decorative banners — stars or equals around a title.
• Template phrases — repeat a unit inside larger strings.
• Not for fixed width — prefer padStart / padEnd when the goal is a target length.
• Not for huge counts — very large count can throw or exhaust memory.

📝 Notes

• repeat(0) returns "" — it does not throw.
• Negative count or Infinity throws RangeError.
• Decimals are truncated toward zero before repeating.
• repeat does not insert separators between copies.
• Very large counts can throw if the result would be too long.
• The method is generic — it can run on other objects that coerce to strings.

💡 Best Practices