Analysis of usage of in operator in javascript_javascript skills

The example in this article describes the usage of in operator in javascript. Share it with everyone for your reference. The specific analysis is as follows:

The

in operator hopes that its left operand is a string or can be converted to a string, and that its right operand is an object; if the right-hand object has an attribute name named the left operand value, then the expression The formula returns true:

var point = {x:1,y:1};
"x" in point //true
"z" in point //false
"toString" in point //true
var ary = [1,2,3];
"0" in ary; //true，ary含有索引0("0"回转换为0)；
1 in ary;  //true,ary含有索引1
3 in ary;  //false

I hope this article will be helpful to everyone’s JavaScript programming design.