Javascript数组循环变量未定义

Question

I am having a bit of trouble with a loop that reads an array:

var myStringArray = [{
  "people": [{
    "id": "123",
    "name": "name 1"
  }, {
    "id": "456",
    "name": "name 2"
  }]
}];

var arrayLength = myStringArray.length;

for (var i = 0; i < arrayLength; i++) {            
  console.log(myStringArray[i].id);
}

Where am I going wrong here?

Answer 1

You need to iterate over the inner array( people property of the first element in the main array).

 var myStringArray = [{ "people": [{ "id": "123", "name": "name 1" }, { "id": "456", "name": "name 2" }] }]; var arrayLength = myStringArray[0].people.length; for (var i = 0; i < arrayLength; i++) { console.log(myStringArray[0].people[i].id); } 

---

Although you can use Array#forEach method.

 var myStringArray = [{ "people": [{ "id": "123", "name": "name 1" }, { "id": "456", "name": "name 2" }] }]; myStringArray[0].people.forEach(function(v) { console.log(v.id); }); 

Answer 2

Access id from object stored in myStringArray[0].

Here is the modified code:-

var myStringArray = [
    {
        "people":[
            {"id":"123","name":"name 1"},
            {"id":"456","name":"name 2"}
        ]
    }
];

var array = myStringArray[0].people,
    arrayLength = array.length;
for (var i = 0; i < arrayLength; i++) {

    console.log(array[i].id);

}

Answer 3

because your array only haw 1 item and its people. and people don't has id property. the people contains two item that every one has their id.

for (var i = 0; i < arrayLength; i++) {
  for(var j = 0; j < myStringArray[i].length; j++)
  {
    console.log(myStringArray[i][j].id);
  } 
}