Who knows why `a=undefined` in #Firefox but `a=1` elsewhere?
<body onload="a=1;document.write('<button onclick=alert(a)>'+a+'</button')">
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Thanks. Twitter will use this to make your timeline better. UndoUndo
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@mathias Thanks!Thanks. Twitter will use this to make your timeline better. UndoUndo
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JavaScript, HTML, CSS, HTTP, performance, security, Bash, Unicode, i18n, macOS.