Pen Settings



CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URLs added here will be added as <link>s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.

+ add another resource


Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource


Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.


Auto Save

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.






// Your average console.log
console.log("Merry Christmas!")

// Most of the time, we're just interested in quickly logging a value. Why not make that process eight keypresses shorter?
// PS: This will work for any method described below as well.
const log = console.log 
log("All I want for Christmas is to type less!")

// We're about to be logging a lot, so let's put these in a nice group"Naughty and Nice Children")

// Sometimes you want to log a few aspects of your state at once. Instead of typing something like :
let naughtyChildren = ["Jeff" , "Joel", "Jim" , "John"]
let niceChildren    = ["Jane" , "Jill" , "Jasmine", "Jaqueline"]

log("Naughty Children" , naughtyChildren)
log("Nice Children" , niceChildren)

// You can simply pass multiple arguments to a log. One nice use case for this syntax is comparing values in arrays. (get screen shot) 
log("Naughty Children " , naughtyChildren, "Nice Children " , niceChildren)

// Alas! This is printing all on one line! This is pretty naughty. We should make it nice by using some formatting.
log("Naughty Children \n" , naughtyChildren, "\n Nice Children \n" , niceChildren)

// End our group
console.groupEnd("Naughty and Nice Children");

// Sometimes you would like to see a trace of your function. Console.trace lets you do just that."Tracing")
let whoGetsCoalInTheirStocking = 
     names => names.forEach( 
                      name => {
                         log(name, "will get coal in their stocking");

  Console.dir will let you view an interactive tree of your object.
  In Chrome this happens automatically, but this is helpful for Firefox/Node environments 
let test = {  test1: { passed : true, difficulty: 10 } , 
              test2: { passed : false, difficulty: 6 } ,
              test3: { passed : false, difficulty: 5 } ,
              test4: { passed : true, difficulty: 4 } ,
              test5: { passed : false, difficulty: 9 } , 
              test6: { passed : true, difficulty: 2 }  

// Our log is getting too long! Let's clear it out. This might be useful if you get a 
// few errors at the beginning of a page while youre developing. Uncomment to see it in action!
// console.clear();

// Here is a nifty trick to measure time.
window.setTimeout( () => {console.timeEnd("start")}, 1000);

  Sometimes you just don't want to see logs anymore, but you're not about to go back 
  through a bunch of code and add some try/catch to everything like you do with all the code you yourself write.
  (ie. maybe a library is throwing an error that you don't find to be too worrisome) 
  One way to handle this situation is to overwrite the console.log method.
  As an added stocking stuffer: 
  If you followed above and saved console.log to a variable (in our case log), you will still get your personal logs!
console.log("Ho ho ho") // Logs

console.log = function(){} // Overwrite console.log function

console.log("Hum hum hum") // Doesn't Log

log("Hum hum hum") // Does Log