korokd

function cloneDeep(objSource) {
  if (objSource instanceof Date) {
      return new Date(objSource);
  }

  const plainObject = {};

  if (!(objSource instanceof Object) || objSource instanceof String) {
      return objSource;
  }

korokd

Title

Things will be explained by examples, since this gist is primarily for myself :P

Short circuit

JavaScript short circuits Comparison Operators. Hence, you may be able to gain performance (?) by using them with this in mind.

AND

If variable a has 70% chance of being truthy and variable b has 50% chance of being truthy, you might prefer to write your if statement as if (b && a) {...} than if (a && b) {...}. Why? Because with the first, 50% of the time the engine will not even have to check for a's value