I’m trying to figure out how to run JavaScript directly within an iframe instead of the main parent window. I have some working code that opens a popup window with a JavaScript testing interface, but when I try to use it with iframes, it keeps executing on the parent page instead of inside the iframe itself.
Here’s my current code that works for the parent window:
javascript:popup=window.open('','TestWindow','width=300,height=200,resizable=yes');popup.focus();with(popup.document){write('<title>JS Runner</title><div><form><textarea name=scriptInput rows=8 cols=30>javascript:</textarea><br><input type=button value=Execute onclick=opener.location=scriptInput.value></form></div>');void(close())}
The problem is that this script targets the parent frame. I need it to run inside a specific iframe on my page. I tried modifying the onclick handler to use opener.document.getElementById('targetFrame').src but that approach failed completely.
Is there a way to modify this code so it executes JavaScript within the iframe content instead of affecting the parent window? Any suggestions would be really helpful.
you can’t run js in a cross-domain iframe - the same-origin policy blocks it. if it’s the same domain, try using document.getElementById('yourIframe').contentWindow.eval(yourCode) or access the document with contentDocument. cross-origin iframes are sandboxed for security reasons tho.
Your problem is you’re trying to manipulate the iframe’s location property - that won’t execute JavaScript properly. You need to access the iframe’s content window directly instead. If the iframe’s on the same domain, change your onclick handler to parent.document.getElementById('targetFrame').contentWindow.eval(scriptInput.value). This runs the code inside the iframe’s context rather than just changing its source. Just heads up - if the iframe has content from a different domain, browser security will block this completely. Also, eval() is risky security-wise, so only use it with code you trust. For same-origin stuff, you can also use the contentDocument property to manipulate DOM elements directly.
Your problem is opener.location - it’s changing the whole page URL instead of running code inside the iframe. I’ve hit this before and here’s what works better: change your popup code to target the iframe’s execution environment directly. Replace opener.location=scriptInput.value with opener.document.getElementById('targetFrame').contentWindow.Function(scriptInput.value.replace('javascript:',''))(). This creates a function in the iframe’s scope and runs it right away. Function constructor is safer than eval and handles that javascript: prefix issue. Just make sure your iframe has a proper id attribute. Won’t work cross-origin though - browser security blocks that.