indexOf vs includes

Compares String.prototype.indexOf against String.prototype.includes for substring searches.

Shazzer Master

Created byhackvertor

Created Jul 4, 2026

Updated Sep 5, 2026

Unable to render tweet button

RSS

Detecting browser...

CategoryJavaScript Syntax

VisibilityPublic

TypePERF

CharsetUTF-8

Code used before fuzz:

var iterations = 2000000;
var s = "hello world";

Snippet A:

s.indexOf("world") !== -1

Snippet B:

s.includes("world")

Sample payloads

s.indexOf("world") !== -1

s.includes("world")

Performance results

Snippet A

s.indexOf("world") !== -1

Snippet B

s.includes("world")

Browser	Snippet A	Snippet B	Winner
1stFirefox157.0	6.00 ms	6.00 ms	Tie
2ndSafari26.6.2	9.00 ms	10.00 ms	Snippet A1.11× faster
3rdMicrosoft Edge154.0.4258.37	10.10 ms	10.00 ms	Snippet B1.01× faster
4thChrome155.0.8059.39	21.30 ms	21.50 ms	Snippet A

Median of 5 trials × 2,000,000 iterations per snippet.

indexOf vs includes

Compares String.prototype.indexOf against String.prototype.includes for substring searches.

Shazzer Master

Created byhackvertor

Created Jul 4, 2026

Updated Sep 5, 2026

Unable to render tweet button

RSS

Detecting browser...

CategoryJavaScript Syntax

VisibilityPublic

TypePERF

CharsetUTF-8

Code used before fuzz:

var iterations = 2000000;
var s = "hello world";

Snippet A:

s.indexOf("world") !== -1

Snippet B:

s.includes("world")

Sample payloads

s.indexOf("world") !== -1

s.includes("world")

Performance results

Snippet A

s.indexOf("world") !== -1

Snippet B

s.includes("world")

Browser	Snippet A	Snippet B	Winner
1stFirefox157.0	6.00 ms	6.00 ms	Tie
2ndSafari26.6.2	9.00 ms	10.00 ms	Snippet A1.11× faster
3rdMicrosoft Edge154.0.4258.37	10.10 ms	10.00 ms	Snippet B1.01× faster
4thChrome155.0.8059.39	21.30 ms	21.50 ms	Snippet A

Median of 5 trials × 2,000,000 iterations per snippet.

Distributed Fuzzing

indexOf vs includes

Sample payloads

Performance results

indexOf vs includes

Sample payloads

Performance results