What is the equivalent of Java s System out println in Javascript

Question

I am writing some tests for Javascript code and I need to dump some messages during the compile process when errors are encountered   Is there any equivalent to Java s System out println   in Javascript   P S   I also need to dump debug statements while implementing tests   UPDATE  I am using a maven plugin on a file containing all merged tests            lt plugin gt               lt groupId gt org codehaus mojo lt  groupId gt               lt artifactId gt exec-maven-plugin lt  artifactId gt               lt version gt 1 1 lt  version gt               lt executions gt                   lt execution gt                   lt phase gt test lt  phase gt                   lt goals gt                       lt goal gt java lt  goal gt                   lt  goals gt                   lt  execution gt               lt  executions gt               lt configuration gt                   lt mainClass gt org mozilla javascript tools shell Main lt  mainClass gt                   lt arguments gt                       lt argument gt -opt lt  argument gt                       lt argument gt -1 lt  argument gt                       lt argument gt   basedir  src main webapp html js test test js lt  argument gt                   lt  arguments gt               lt  configuration gt           lt  plugin gt    UPDATE II  I tried console log         but I get   js   src main webapp html js concat tests all js   line 147  uncaught JavaScript runtime exception  ReferenceError   console  is not defined   The code I am testing is a set of functions  like in a library   I am using QUnit

User · Answer

I found a solution   print  My message here

User · Answer

There isn t one  at least  not unless you are using a  developer  tool of some kind in your browser  e g  Firebug in Firefox or the Developer tools in Safari  Then you can usually use console log   If I m doing something in  say  an iOS device  I might add a  lt div id  debug    gt  and then log to it

User · Answer

In java System out println   prints something to console  In javascript same can be achieved using console log     You need to view browser console by pressing F12 key which opens developer tool and then switch to console tab

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You can always simply add an alert   prompt anywhere in a function   Especially useful for knowing if a function was called  if a function completed or where a function fails   alert  start of function x    alert  end of function y    alert  about to call function a    alert  returned from function b      You get the idea

User · Answer

Essentially console log  Put a message here    if the browser has a supporting console   Another typical debugging method is using alerts  alert  Put a message here     RE  Update II  This seems to make sense  you are trying to automate QUnit tests  from what I have read on QUnit this is an in-browser unit testing suite library  QUnit expects to run in a browser and therefore expects the browser to recognize all of the JavaScript functions you are calling    Based on your Maven configuration it appears you are using Rhino to execute your Javascript at the command line terminal  This is not going to work for testing browser specifics  you would likely need to look into Selenium for this  If you do not care about testing your JavaScript in a browser but are only testing JavaScript at a command line level  for reason I would not be familiar with  it appears that Rhino recognizes a print   method for evaluating expressions and printing them out  Checkout this documentation   These links might be of interest to you   QUnit and Automated Testing  JavaScript Unit Tests with QUnit

User · Answer

I m using Chrome and print   literally prints the text on paper  This is what works for me   document write  My message

User · Answer

console log     Chrome  Safari  and IE 8  come with built-in consoles  as part of a larger set of development tools   If you re using Firefox  getfirebug com

User · Answer

I m also about to ask the same question  But from what I ve learned from codeacademy com below code is enough to display the output or text   print  hello world

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