为什么我的对象在for循环中从最后到第一

Question

i confuse about array

my data is

and my for loop

 for (var data in statInfo["segment"][0]) {
       console.log(data)
 }

and my result is

data print is

segment5 segment4 segment3 segment2 segment1

thank you

Answer 1

Enumeration of object properties is not alphabetical.

In fact it is left to implementations to decide .

Most browsers implement according to order of property creation IIRC.

If you need ordering use an Array , Map or Set .

Finally, in ES2015, you can make an object iterable by defining your own iteration function, which can have any order or enumeration you need.

 var obj = { foo: '1', bar: '2', bam: '3', bat: '4', }; obj[Symbol.iterator] = iter.bind(null, obj); function* iter(o) { var keys = Object.keys(o); for (var i=0; i<keys.length; i++) { yield o[keys[i]]; } } for(var v of obj) { console.log(v); } // '1', '2', '3', '4'