>>>

this.length >>> 0表示什么？

var a = 222
var b = a>>>0
console.log(a, b, typeof(a), typeof(b))
var a = -222
var b = a>>>0
console.log(a, b, typeof(a), typeof(b))
var a = '222'
var b = a>>>0
console.log(a, b, typeof(a), typeof(b))
var a = '222aaa'
var b = a>>>0
console.log(a, b, typeof(a), typeof(b))
var a = [1, 2, 3] 
var b = a>>>0
console.log(a, b, typeof(a), typeof(b))