Console assert()
Examples
Write a message to the console:
console.assert(x + y == 11, "Expression returned false");
Try it Yourself »
Write an object to the console:
const myObj = {firstname:"John", lastname:"Doe"};
console.assert(x + y == 11, myObj);
Try it Yourself »
console.assert(x + y == 11, myObj);
More examples below.
Description
The assert() method writes a message to the console
if an expression evaluates to false.
Syntax
console.assert(expression, message)
Parameters
Parameter
Description
expression
Required.
Any expression.
If the expression evaluates to
Any expression.
If the expression evaluates to
false, a message
is written in the console.
message
Required.
The message to write in the console.
The message to write in the console.
More Examples
Check for an element:
console.assert(document.getElementById("demo"), "You have no element with ID 'demo'");
Try it Yourself »
Write an array to the console:
const myArr = ["Orange", "Banana", "Mango", "Kiwi" ];
console.assert(x + y == 11, myArr);
Try it Yourself »
console.assert(x + y == 11, myArr);
Browser Support
console.assert() is supported in all browsers:
| Chrome | Edge | Firefox | Safari | Opera | IE |
| Yes | Yes | Yes | Yes | Yes | Yes |