setTimeout behaviour with blocking code

Question

This is my test code (fiddle here):

console.log(\'Before wait\');
setTimeout(function () { console.log(\'Yo!\'); }, 1000);
var start = Date.now();
while (Dat         


        

Answer 1

When you run the busy-waiting loop after the setTimeout call, you don't let time for your "Yo!" to print out, because the Javascript runtime is busy with your loop (actualy the empty statement also makes it busy because of continues evaulaation of the loop condition).

You should always avoid such a busy-waiting loop, because until that finishes, nothing else can be called or run in that window.