Iterator.concat()Baseline · Newly available
The Iterator.concat() JavaScript method returns an iterator that yields values from a sequence of iterators, exhausting each iterator before moving on to the next.
Works in the latest version of every major browser, but older devices may not support it yet. Baseline since Mar 24, 2026.
Browser support
DesktopChrome
1–145Not supported
146+Supportedsince Mar 10, 2026
Current: 155Edge
12–145Not supported
146+Supportedsince Mar 13, 2026
Current: 154Firefox
1–146Not supported
147+Supportedsince Jan 13, 2026
Current: 157Safari
1–26.3Not supported
26.4+Supportedsince Mar 24, 2026
Current: 27MobileChrome Android
18–145Not supported
146+Supportedsince Mar 10, 2026
Current: 155Firefox Android
4–146Not supported
147+Supportedsince Jan 13, 2026
Current: 157Safari iOS
1–26.3Not supported
26.4+Supportedsince Mar 24, 2026
Current: 27How to use
Every current browser supports this, but it only became Baseline on Mar 24, 2026. Use it as a progressive enhancement, or keep a fallback if you support older devices.
Example
Full syntax and examples are on MDN: concat.
Feature detection
JS · check before using
if ("concat" in Iterator || ("prototype" in Iterator && "concat" in Iterator.prototype)) {
// Iterator.concat is available
}