What is “assert” in JavaScript?

Question

What does assert mean in JavaScript?

I’ve seen something like:

assert(function1() && function2() && function3(), \"some          


        

Answer 1

Previous answers can be improved in terms of performances and compatibility.

Check once if the Error object exists, if not declare it :

if (typeof Error === "undefined") {
    Error = function(message) {
        this.message = message;
    };
    Error.prototype.message = "";
}

Then, each assertion will check the condition, and always throw an Error object

function assert(condition, message) {
    if (!condition) throw new Error(message || "Assertion failed");
}

Keep in mind that the console will not display the real error line number, but the line of the assert function, which is not useful for debugging.