The JavaScript console log() is a function that writes a message to log on to the console. It is used by the web developer for debugging the app.
Log message will not display anything on the screen. It logs a message to a debugging console.
console.log("Hello");Console.log JavaScript example
Simple example code of console.log() function in JavaScript use to print variables.
<!DOCTYPE html>
<html>
<body>
<script>
var num = 1000;
console.log(num);
var str = "Hello World!"
console.log(str);
</script>
</body>
</html> Output:
Passing a function as an argument:
<script>
function func() {
return (5 * 10);
}
console.log(func());
</script>Passing a number with the message as an argument
<script>
var num = 2;
console.log("The value of num is " + num);
</script>Passing a string with the message as an argument
<script>
var str = "Hello";
console.log("The value of str is " + str);
</script>Write an object to the console:
const myObj = {firstname:"John", lastname:"Doe"};
console.log(myObj); Write an array to the console:
const myArr = ["A", "B", "C", "D"];
console.log(myArr);Print a Sentence
console.log("I love JS");Multiple Values
Instead of typing console.log() three times we can include them all.
let x = 1
let y = 2
let z = 3
console.log("x:", x, "y:", y, "z:", z)Variables within the log
In this example, %s refers to a string option included after the initial value. The %d refers to a digit option included after the initial value.
console.log("%s is %d years old.", "John", 29)Variations of logs
There are a few variations of logs.
console.log('Console Log')
console.info('Console Info')
console.debug('Console Debug')
console.warn('Console Warn')
console.error('Console Error')Do comment if you have any doubts or suggestions on this JS console log topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version