What is window.console && console.log?

Question

 if (open_date) {
        open_date = get_date_from_string(open_date);
        window.console && console.log(open_date);
        window.console && console.log(cancel_until);

What is window.console && console.log ? Does it have to be in the code? Through this script does not work on IE (all version) --> IE runs javascript only after pressing F12

possible duplicate of [What is console.log?](http://stackoverflow.com/questions/4539253/what-is-console-log) — John Dvorak, Jan 28 '13 at 11:54

jAndy · Answer 1 · 2013-01-28T12:00:05.550

17

The rightside-expression will only get evaluated if the leftside-expression is truthy. Thats how the logical AND operator works.

Its basically short for

if( window.console ) {
    console.log( open_date );
}

As you might guess correctly, it's a common pattern for this case, because the console object might not be available on every browser (especially mobiles).

edited Jan 28 '13 at 12:00

answered Jan 28 '13 at 11:54

jAndy

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@Andy, very good answer (+1). It would be also good to mention that the code needs to be there as not all browsers support `console` (OP question `Does it have to be in the code?`) – Tom Jan 28 '13 at 11:57
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I still prefer this approach: `console = window.console || {log:function(){}/*,...*/}` – John Dvorak Jan 28 '13 at 12:00

Jakob · Answer 2 · 2013-01-28T13:23:49.680

5

1.) What is window.console && console.log ?

console.log refers to the console object used for debugging. for firefox i use firebug for example.

but if the console is not available the script will crash. so window.console checks if the console object is there and if so it uses its log function to print out some debug information.

2.) Does it have to be in the code?

no, its only for debugging purpose

edited Jan 28 '13 at 13:23

answered Jan 28 '13 at 12:09

Jakob

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score 4 · Answer 3 · answered Oct 29 '14 at 17:32

window.console && console.log(open_date);

The above code is just short for an if conditional statement. It doesn't have to be there. it is for debugging purposes. For most browsers, you can hit F-12 to open the browser debug console. Chrome has a debug console built in. Firefox has an extension called FireBug that you can use. Below is the equivalent statement without the '&&'.

if (window.console) console.log(open_date);

I prefer to add the following code at the beginning of my javascript code so that I do not have to have these "if" statements all over the place. It really saves space and removes potential errors.

if (typeof console == "undefined") { window.console = {log: function() {}}; }

Jon Dvorak's comment above contains an elegant alternative way of doing this:

console = window.console || {log:function(){}}

score 1 · Answer 4 · answered Jan 28 '13 at 11:55

1

Console.log is a logger for browser which logs the messages on browser console. EDIT: Console.log is not supported for lower versions of Internet Explorer

answered Jan 28 '13 at 11:55

Abhijeet Pawar

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score 0 · Answer 5 · answered Jan 27 '16 at 15:18

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This condition is used to prevent errors on IE ... because, unfortunately, in IE (version 8) we cannot use console.log("") .... however testers still view the logs on Chrome ...

answered Jan 27 '16 at 15:18

Mohamed Taboubi

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What is window.console && console.log?

5 Answers5

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