How can I allow download in sandboxed iframe using Javascript?

Question

<iframe sandbox="allow-forms allow-scripts allow-same-origin" src="HTML_HERE" id="iframe"></iframe>

This is the sandboxed iframe, you are not allowed to modify this and add 'allow-downloads' or any sandbox properties. You need Javascript to sove this.

Answer 1

'allow-downloads' is newly introduced value for the sandbox attribute in the iframe.

sandbox="allow-downloads"

Reference: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#browser_compatibility