If you are willing to accept an interference for the user,
you could use the debugger statement, as it is available in all major browsers.
Side note: If the users of your app are interested in console usage, they're probably familiar with dev tools, and will not be surprised by it showing up.
In short, the statement is acting as a breakpoint, and will affect the UI only if the browser's development tools is on.
Here's an example test:
<body>
<p>Devtools is <span id='test'>off</span></p>
<script>
var minimalUserResponseInMiliseconds = 100;
var before = new Date().getTime();
debugger;
var after = new Date().getTime();
if (after - before > minimalUserResponseInMiliseconds) { // user had to resume the script manually via opened dev tools
document.getElementById('test').innerHTML = 'on';
}
</script>
</body>
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
