Not sure if this is what you are looking for, but in Chrome (and Firefox if Firebug is installed) you can use the built-in JavaScript debugger . This causes execution to pause, and it is as efficient as setting a breakpoint. For example, the following will be broken at each iteration of the loop: you can check the value of i (a stupidly simple example):
for(var i = 0; i < 10; i++) { debugger; console.log(i); }
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