setInterval with Infinity

Question

So If i am doing:

setInterval(function(){

   console.log("1");

},Infinity);

It keeps on logging 1 as if it is a for loop. Why is that behaviour?

Answer 1

When the float/number Infinity needs to be converted to a 32-bit integer value in JavaScript, as it does for setTimeout, it's converted to zero:

console.log(typeof Infinity); // number
console.log(Infinity | 0);    // 0

ECMA-262 6e Section 7.1.5 ToInt32 ( argument )

The abstract operation ToInt32 converts argument to one of 2³² integer values in the range −2³¹ through 2³¹−1, inclusive. This abstract operation functions as follows:

1. Let number be ToNumber(argument).
2. ReturnIfAbrupt(number).
3. If number is NaN, +0, −0, +∞, or −∞, return +0.
4. [...]