Convert to integer with a default value of 0.

convert_to_int_with_default_zero.js

(function(priority) {console.log(priority); return priority && + priority | 0 || 0; })()
// undefined
// 0

(function(priority) {console.log(priority); return priority && + priority | 0 || 0; })(45)
// 45
// 45

(function(priority) {console.log(priority); return priority && + priority | 0 || 0; })('a')
// a
// 0

(function(priority) {console.log(priority); return priority && + priority | 0 || 0; })(true)
// true
// 1

(function(priority) {console.log(priority); return priority && + priority | 0 || 0; })(false)
// false
// 0

(function(priority) {console.log(priority); return priority && + priority | 0 || 0; })(0.3)
// 0.3
// 0

(function(priority) {console.log(priority); return priority && + priority | 0 || 0; })(function() {})
// function (){}
// 0