How to use for..Of to traverse objects in JS

for…of Is to allow traversal of a iterator Data structure of the interface （ Array ） And return the value of each item

1） What needs to be traversed is the class array object , array-based Array.from Converted to an array

        var obj={
    
            0:1,
            1:2,
            2:3,
            length:3
        }
        obj=Array.from(obj)
        for(let value of obj){
    
            console.log(value);//1 2 3
        }

2） The object to be traversed is not an object , Add one to the object Symbol.iterator attribute （ default iterator Interface ）, Point to the iterator

iterator Ergodic process ：

• Create a pointer object , Point to the start of the current data structure
• The first call to the next Method , You can point a pointer to the first member of a data structure
• The second call to the next Method , Pointer to the second member of the data structure
• Constantly calling the pointer object next Method , Until it points to the end of the data structure

Every time you call next Method , Will return the current member information of the data structure , Returns a containing value and done Objects with two properties

• value： The value of the current member
• done： It's a Boolean value , Indicates whether the traversal ends

        var Person={
    
            name:'jack',
            age:18,
            height:185,
            weight:160,
            sex:' male '
        }
        Person[Symbol.iterator]=function(){
    
            var key=Object.keys(this)
            var index=0
            return{
    
                next() {
    
                    if (index < key.length) {
    
                        return {
     value: [key[index++]], done: false }
                    } else {
    
                        return {
     value: undefined, done: true }
                    }
                }
            }
        }
        for (item of Person) {
    
            console.log(item);
        }