Also, choosing JavaScript as your coding language means that you need a testing framework. This is because unit testing isn't built into the language. This is okay. A few utility functions like assert() get the job done.

/**
 * The assert function verifies if a condition is truthy.
 *
 * @param {boolean} condition - The condition that indicates if the
 * assertion passes.
 * @param {string} description - The message describing the assertion.
 */
function assert(condition: boolean, description: string): void {
   if (!condition) throw new Error(description);
}

Another function I really like is the xor() function, because we can negate assertions using an exclusive or operation.

function xor(a: boolean, b: boolean): boolean {
  return (a && !b) || (!a && b);
}

And now, we can verify a contrapositive assertion.

const negated: boolean = true;
const condtion: boolean = /* some truthy assertion of application state. */;

// now perform the assertion
assert(xor(condition, negated), "This is a negated assertion.");

This example is obviously contrived, but a bunch of tiny little tools really help. You don't need a testing framework. You need responsibility.

If you can find an example where you simply should delay testing, please show me. Every line of code is an opportunity to free yourself from the shackles of chaos, and you are the person who unlocks them.