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Last active Dec 16, 2015
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assert() for Javascript
function AssertionError(msg) {
this.message = msg || ""; = "AssertionError";
AssertionError.prototype = Error.prototype;
/* Call assert(cond, description1, ...)
An AssertionError will be thrown if the cond is false. All parameters will be logged to the console,
and be part of the error.
function assert(cond) {
if (! cond) {
var args = ["Assertion error:"].concat(, 1));
console.error.apply(console, args);
// This is mostly for Firefox, and should perhaps be conditional on that;
// this is because the standard Web Console often doesn't show proper stacks for errors
// (depending on where the error was thrown)
if (console.trace) {
throw new AssertionError(args.join(" "));
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