What is “assert” in JavaScript?

In JavaScript, assert is not a language keyword but a function commonly used in testing and debugging to verify that a certain condition holds true. The most popular implementation comes from the Node.js assert module, which allows developers to write tests and catch unexpected behavior in their code. When an assertion fails, it throws an error, letting you know that something didn’t work as expected.

For example:

const assert = require('assert');

let x = 5;

assert(x === 5);  // passes silently

assert(x === 10); // throws AssertionError

Here, the first assertion succeeds because the condition is true, but the second one throws an error since the condition is false.

Key points about assert in [removed]

• Purpose: Ensures that a condition or expression evaluates to true. If not, it raises an error.
  
• Node.js usage: Available through the built-in assert module.
  
• Testing: Widely used in unit tests to validate expected outcomes.
  
• Error handling: Helps catch bugs early by signaling when assumptions in the code fail.
  
• Custom messages: You can provide a message for clearer debugging.
  

Example with a message:

  assert.strictEqual(2 + 2, 4, "Math is broken!");

 While assert is helpful for debugging and testing, it should not replace proper error handling in production code. Assertions are best suited for development and testing environments where you want quick feedback if something unexpected occurs.