found drama

Inspired by some recent entanglements with a vendor’s API:

	var n = new Number(1);
	alert(n); // 1
	typeof n; // object
	n instanceof Number; // true
	var nn = 1;
	alert(nn); // 1
	typeof nn; // number
	n instanceof Number; // false
	n == nn; // true
	typeof n == typeof nn; // false
	n++;
	nn++;
	alert(n); // 2
	alert(nn); // 2
	n == nn; // true
	typeof n; // number
	typeof nn; // number
	typeof n == typeof nn; // true

view raw number-constructors.js hosted with by GitHub

The type coercion will ultimately work in your favor but the main point is that the type coercion has to take place in the first place. Granted, it is probably an edge case ¹ to do something like:

	var n = new Number(x); // where x is a global storing an incrementer
	function doMath(a){
	if (typeof a == "number") {
	return a + x;
	}
	}
	doMath(n);

view raw gistfile1.js hosted with by GitHub

…but you never know. There’s some strange code out there ².

1. And therefore you get what you deserve?[]
2. And by that I mean: Don’t be one of the ones writing it.[]

About Rob Friesel

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