循环遍历json中的多个项目并分配变量

Question

I'm trying to loop through some json. The json result looks like this:

{
  "items": [{
    "metafield1": "May 22 2019"
  }, {
    "metafield1": null
  }, {
    "metafield1": null
  }, {
    "metafield1": "May 20 2019"
  }]
}

I'm getting this in an ajax call that then assigns a variable and then checks if the variable exists.

$.ajax({
  type: 'GET',
  url: '/cart?view=alternate.json',
  success: function(result) {
    var obj = JSON.parse(result);
    var del_date = obj.metafield1;
    if (del_date !== null) {
      // do something
    }
  }
})

At first I only had one item in the json so this worked fine, but now as you can see I've got multiple so I need to loop through them and eventually compare them so basically I need to store each one of them as a variable. Any ideas how to do this?

Answer 1

You can handle your string like this use map function with [] operator

var string = '[{ "metafield1": "May 22 2019" } , { "metafield1": null } , 
 { "metafield1": null } , { "metafield1": "May 20 2019" } ]';

var metafields = JSON.parse(string).map(function(v){ return v['metafield1']; });

console.log(metafields);

Updated with new object

let result = {
  "items": [{
    "metafield1": "May 22 2019"
  }, {
    "metafield1": null
  }, {
    "metafield1": null
  }, {
    "metafield1": "May 20 2019"
  }]
};

string = JSON.stringify(result.items);

var metafields = JSON.parse(string).map(function(v){ return v['metafield1']; });

console.log(metafields);

 let result = { "items": [{ "metafield1": "May 22 2019" }, { "metafield1": null }, { "metafield1": null }, { "metafield1": "May 20 2019" }] }; //console.log(JSON.stringify(result.items)); //var string = '[{ "metafield1": "May 22 2019" } , { "metafield1": null } , { "metafield1": null } , { "metafield1": "May 20 2019" } ]'; string = JSON.stringify(result.items); var metafields = JSON.parse(string).map(function(v){ return v['metafield1']; }); console.log(metafields); 

Answer 2

This should be working :

 // we set a variable x = to your JSON variable var x = { "items": [{ "metafield1": "May 22 2019" }, { "metafield1": null }, { "metafield1": null }, { "metafield1": "May 20 2019" }] }; // we update x to be equal to your item field from the object, x is now an array instead of an object x = x["items"]; for (var i of x) { if (i.metafield1 !== null) { console.log(i.metafield1); // your code here } }