console.log

console

The better way to see messages from the JavaScript running in the browser is to use the console.log() function and open the console.

See the documentation of console

examples/js/console_script.html

Open the console!
<script>

console.log("Hello World");

console.debug("A debug message");
console.info("An info message");
console.warn("A warning");
console.error("This is an error message");

</script>

To open the JavaScript console

Chrome Mac: Command-Option-J
Chrome Windows: Ctrl-Shift-J
Firefox Mac: Command-Option-K
Firefox Windows: Ctrl-Shift-K
Internet Explorer: F12
Safari: Command-Option-C

Run it with Node.JS

Run it in the editor