JavaScript controls most of what websites do beyond plain text. Forms, animations, dropdowns, video players. If it's off in Safari, a lot of sites just look broken. Enabling it on iPhone takes about 15 seconds.
It's usually on by default. You only need to enable it if it got toggled off somehow, or if you're troubleshooting a broken site.
Enable JavaScript in Safari
Open Settings. Scroll down and tap Apps, then find Safari. On older iOS just scroll directly to Safari. Scroll the Safari settings to the bottom and tap Advanced.
You'll see a toggle for JavaScript. Make sure it's on (green). That's it. Close settings and your sites should work normally.
Enable JavaScript in Chrome on iPhone
Chrome on iOS doesn't let you disable JavaScript at all. It's always on. So if a site isn't working in Chrome iOS, JavaScript is not the problem – look at other settings or extensions.
Worth knowing because some people assume the toggle exists like it does on Chrome desktop.
Why a site still doesn't work
You enabled JavaScript and the site is still broken. Common causes besides JavaScript:
- Cookies are blocked for that site
- Pop-ups are blocked and the site needs to open one
- Content blockers (ad blockers, privacy apps) are filtering scripts
- The site has been pulled or is down for maintenance
- Your iPhone iOS is too old for the site's modern code
Check those next. Content blockers are the most common culprit. They live in Settings then Safari then Extensions. Try toggling each off to find which one is breaking the site.
Disable JavaScript for privacy reasons
Some people turn off JavaScript intentionally for privacy. Tracking scripts, fingerprinting, and ads all rely on JavaScript. Disabling it stops most of that.
The trade-off – many modern sites become unusable. Twitter and Facebook are basically blank pages without JavaScript. News sites load text but no images or interactive features. So this is an aggressive option.
To turn it off, same path as enabling – Settings, Safari, Advanced, toggle JavaScript off. Easy to flip back on if a site you need breaks.
Check if JavaScript is working
Visit a test page like enable-javascript.com. If JavaScript is working, the page shows a green message saying it's enabled. If it's off, you get a red warning instead.
Quick way to confirm without troubleshooting blind. Bookmark it if you switch JavaScript on and off often for privacy reasons.
Per-site JavaScript control
iOS Safari doesn't let you allow JavaScript only for specific sites. It's all or nothing. Desktop browsers like Chrome and Firefox have per-site controls in their settings but the iPhone versions don't.
If you want granular control, you can use a third-party browser like Brave or Firefox Focus which have better script blocking options on iOS.
Which site is not working for you? Drop the URL in comments and I'll check if it's a JavaScript issue or something else.