strange behaviour of variable named “status” in javascript

Answer 1

It's because you run your code in global context! var bound variables are bound to the function scope. If you have no function you are in global context, which means in a browser you are on the window object.

This code will log Demo:

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Now your code breaks because window.status is reserved.

An easy fix is to surround your code by a function to provide a new context for your variables, which is always good practice.