This is JavaScript Tips on Objects and Array and their For loop.
In JavaScript, there is an Object and represented as:
var someObj = {name:"YongHao", age:25}
There is an Array and represented as:
var someArr = [1,2,3,4]
Use normal for loop only for Array, and use for…in only for Object.
For example, for Object
var someObj = {name:"YongHao", age:25} for(var i in someObj) { console.log(i + ' - ' + someObj[i]); }
We get:
name – YongHao
age – 25
For Array
var someArr = [1,2,3,4] for(var i = 0; i < someArr.length; i++) { console.log(i + ' - ' + someArr[i]); }
We get:
0 - 1
1 - 2
2 - 3
3 - 4
Do not use for...in to Array, if you do:
var someArr = [1,2,3,4] for(var i in someArr) { console.log(i + ' - ' + someArr[i]); }
It may return good result, but not recommended, as i now is a string but not an integer.