如何循环JSON数组？

Question

I have some JSON-code which has multiple objects in it:

[
    {
        "MNGR_NAME": "Mark",
        "MGR_ID": "M44",
        "EMP_ID": "1849"
    },
    {
        "MNGR_NAME": "Steve",
        "PROJ_ID": "88421",
        "PROJ_NAME": "ABC",
        "PROJ_ALLOC_NO": "49"
    }
]

My JSON loop snippet is:

function ServiceSucceeded(result) 
{       
  for(var x=0; x<result.length; x++) 
  {      

  }    
}

Could you please let me know how to check there is no occurence of "MNGR_NAME" in the array. (It appears twice in my case.)

Answer 1

You need to access the result object on iteration.

for (var key in result)
{
   if (result.hasOwnProperty(key))
   {
      // here you have access to
      var MNGR_NAME = result[key].MNGR_NAME;
      var MGR_ID = result[key].MGR_ID;
   }
}

Answer 2

You could use jQuery's $.each :

    var exists = false;

    $.each(arr, function(index, obj){
       if(typeof(obj.MNGR_NAME) !== 'undefined'){
          exists = true;
          return false;
       }
    });

    alert('Does a manager exists? ' + exists);

Returning false will break the each, so when one manager is encountered, the iteration will stop.

Answer 3

Note that your object is an array of JavaScript objects. Could you use something like this?

var array = [{
    "MNGR_NAME": "Mark",
    "MGR_ID": "M44",
    "EMP_ID": "1849"
},
{
    "MNGR_NAME": "Steve",
    "PROJ_ID": "88421",
    "PROJ_NAME": "ABC",
    "PROJ_ALLOC_NO": "49"
}];

var numberOfMngrName = 0;
for(var i=0;i<array.length;i++){
    if(array[i].MNGR_NAME != null){
        numberOfMngrName++;
    }
}

console.log(numberOfMngrName);

Answer 4

Use ES6...

myobj1.map(items =>
{
if(items.MNGR_NAME) {
return items.MNGR_NAME;
}else {
//do want you want.
}    
})

Thanks.

Answer 5

This will find the number of occurrences of the MNGR_NAME key in your Object Array :

var numMngrName = 0;

$.each(json, function () {
    // 'this' is the Object you are iterating over
    if (this.MNGR_NAME !== undefined) {
        numMngrName++;
    }
});

Answer 6

Within the loop result[x] is the object, so if you wanted to count a member that may or may not be present;

function ServiceSucceeded(result)
{
  var managers = 0
  for(var x=0; x<result.length; x++)
  {
        if (typeof result[x].MNGR_NAME !== "undefined")
            managers++;
  }
  alert(managers);
}

Answer 7

You could use $.each or $.grep, if you also want to get the elements that contain the attribute.

filtered = $.grep(result, function(value) {
    return (value["MNGR_NAME"] !== undefined)
});
count = filtered.length

Answer 8

You can iterate over the collection and check each object if it contains the property:

var count = 0;
var i;
for(i = 0; i < jsonObj.length; i += 1) {
    if(jsonObj[i]["MNGR_NAME"]) {
        count++;
    }
}

Working example: http://jsfiddle.net/j3fbQ/