How to set a JavaScript breakpoint from code in Chrome

Question

I want to force the Chrome debugger to break on a line via code  or else using some sort of comment tag such as something like console break

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This gist Git pre-commit hook to remove stray debugger statements from your merb project maybe useful if want to remove debugger breakpoints while commit

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debugger is a reserved keyword by EcmaScript and given optional semantics since ES5  As a result  it can be used not only in Chrome  but also Firefox and Node js via node debug myscript js   The standard says      Syntax  DebuggerStatement       debugger         Semantics      Evaluating the DebuggerStatement production may allow an implementation to cause a breakpoint when run under a debugger  If a debugger is not present or active this statement has no observable effect       The production DebuggerStatement   debugger   is evaluated as follows          If an implementation defined debugging facility is available and enabled  then         Perform an implementation defined debugging action    Let result be an implementation defined Completion value       Else         Let result be  normal  empty  empty        Return result       No changes in ES6

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On the  Scripts  tab  go to where your code is  At the left of the line number  click  This will set a breakpoint   Screenshot     You will then be able to track your breakpoints within the right tab  as shown in the screenshot

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It is possible and there are many reasons you might want to do this  For example debugging a javascript infinite loop close to the start of the page loading  that stops the chrome developer toolset  or firebug  from loading correctly   See section 2 of    http   www laurencegellert com 2012 05 the-three-ways-of-setting-breakpoints-in-javascript   or just add a line containing the word debugger to your code at  the required test point

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There are many ways to debug JavaScript code  Following two approaches are widely used to debug JavaScript via code   Using console log   to print out the values in the browser console   This will help you understand the values at certain points of your code  Debugger keyword  Add debugger  to the locations you want to debug  and open the browser s developer console and navigate to the sources tab    For more tools and ways in which you debug JavaScript Code  are given in this link by W3School

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As other have already said  debugger  is the way to go  I wrote a small script that you can use from the command line in a browser to set and remove breakpoint right before function call   http   andrijac github io blog 2014 01 31 javascript-breakpoint

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Set up a button click listener and call the debugger   Example      myBtn   click function      debugger           Demo  http   jsfiddle net hBCH5   Resources on debugging in JavaScript   http   www laurencegellert com 2012 05 the-three-ways-of-setting-breakpoints-in-javascript  http   berzniz com post 78260747646 5-javascript-debugging-tips-youll-start-using-today

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You can set debug functionName  to debug functions as well   https   developers google com web tools chrome-devtools javascript breakpoints function

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Breakpoint  - breakpoint will stop executing  and let you examine JavaScript values  After examining values  you can resume the execution of code  typically with a play button   Debugger  - The debugger  stops the execution of JavaScript  and callsthe debugging function  The debugger statement suspends execution  but it does not close any files or clear any variables   Example - function checkBuggyStuff       debugger     do buggy stuff to examine

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I wouldn t recommend debugger  if you just want to kill and stop the javascript code  since debugger  will just temporally freeze your javascript code and not stop it permanently   If you want to properly kill and stop javascript code at your command use the following   throw new Error  This error message appears because I placed it

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You can use debugger  within your code   If the developer console is open  execution will break   It works in firebug as well

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You can also use debug function   to break when function is called   Command Line API Reference  debug

[javascript] How to set a JavaScript breakpoint from code in Chrome?

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