Javascript in a framed asset can no longer alter the DOM of the hosting page; here our asset attempts to add a green border around the frame. Because the frame is sandboxed, the browser will enforce security limits.
https://wiki.dbbs.co/assets/framed/frame.html
framed
//misty-landmine.glitch.me/?load=examples/Wheel+Diagram.json&fullScreen=1&viewOnly=1&editLink=1®ionOfInterest={"x":[-6,6],"y":[-1,3]}
This diagram from Apparatus 
is hosted at glitch.com with some basic CORS headers.
https://c8058f00bfdabfebb3211a9a60b73dd83cb06c79.mdnplay.dev/en-US/docs/Web/API/HTML_Drag_and_Drop_API/runner.html?uuid=c8058f00bfdabfebb3211a9a60b73dd83cb06c79&state=jVLBbtswDP0VQicXyBzk2jUBtqVAC3S3nAZdNIu2NaiUINHZiqL%2FPtJugq1Yu15sSeR7fHzkoxn5PppLc5Uh%2BK01eWMN%2BOKGwX2PKA9cJrRmdxhDBYx4j8Qgx3NKe7XOO0snPLsyIAtgX1KGb4lwiZuV6WqVQnL4of9%2Boo5DopmpCoxvHPmIpcHjBTxaAliv4ZP34EPfY9G6%2FJCxQupnDHjHTtPw2OrxUBxVSWwr8l7ujYjBX7zO0QWyZqV5i7o2EGE5SPDi4zsI1KG%2F8WliLDeHr3f%2FwUsM4JllKuFDDFWsWS3vf9D9FDn71E1qbhtT59SYdizYz7la5cmSpS5RZcgb2II%2FpQvB9TKWzw%2B3vlkmqIi8aZ3310eJ3EldlBoSPbutHb20XmFLjUXZm3VOk1aQJZnVF0cdxpk0HbFATcCjY3mQTegcQR8KWnpu%2BhVtilRp8xZsd8siiFW5oGbvsXdT5Ga2RD9vsaX8TiaApWudovT8cp7DPxfqPPuThJyRfKPIszpZdh7FNNn3GIaRzdNv