Remove undefined keys from json array

Question

I have the following JS array. What's the best way to remove all rows with undefined keys?

json=[{email: "1234569@hhh.pt", first: "Joao", last: "Bastos", gender: "Male", phone: "3.51939e+11"},
      {email: "", first: undefined, last: undefined, gender: undefined, phone: undefined}, 
      (...)];

I've tried the following code but is not working. What am I doing wrong?

cleanEmptyRows(json){

var i=0;
var row_to_remove=[];

json.forEach(function(element) {
    for (var key in element) {
        if(element[key]==null){
        row_to_remove.push(i);
        break;
        }
    }
    i++;
});


row_to_remove.forEach(function(element){
    var index = json.indexOf(element);
    if (index > -1) {
        json.splice(index, 1);
    }
});

JSON is a string representation of a JavaScript object, not an array. — crashmstr, Jun 06 '19 at 19:17
There's no JSON in this question. Not to mention, JSON is a **string** representation. To name a variable `json` that *isn't a string* is quite misleading. Not an answer but just a note that you may want to reconsider that :) — Tyler Roper, Jun 06 '19 at 19:34

Prince Devadoss · Accepted Answer · 2019-06-06T19:26:57.393

Simple solution JSON.parse(JSON.stringify(x)),

var t = [{email: "1234569@hhh.pt", first: "Joao", last: "Bastos", gender: "Male", phone: "3.51939e+11"},
      {email: "", first: undefined, last: undefined, gender: undefined, phone: undefined}];

     
console.log(JSON.parse(JSON.stringify(t)));

If you want to remove the entire row, you can follow the below code,

var t = [{email: "1234569@hhh.pt", first: "Joao", last: "Bastos", gender: "Male", phone: "3.51939e+11"},
      {email: "", first: undefined, last: undefined, gender: undefined, phone: undefined},
      {email: "1234569@hhh.pt", first: "Joao", last: "Bastos", gender: "Male", phone: undefined}];

var resultArray = t.filter((row) => {
    var ignoreValue = Object.values(row).some(elem => elem === undefined);
    return !ignoreValue ? true : false;
});
console.log(resultArray);

Simple and effective, I like the `JSON.parse(JSON.stringify(value))`! The most simple I've seen so far which also handles removing undefined values inside objects that are contained into arrays! Thanks :) — maxime1992, Oct 09 '20 at 08:54

JerMe · Answer 2 · 2019-06-06T19:33:42.637

One simple way is to stringify and parse the JSON.

let jsonTest = { foo: 'foo', bar: undefined };
let allDefined = JSON.parse(JSON.stringify(jsonTest));

You could also do it by deleting undefined properties. You could make it recursive if you don't have a flat object.

let jsonTest = { foo: 'foo', bar: undefined };
Object.keys(jsonTest).forEach((key) => {

    if (typeof jsonTest[key] == 'undefined') { 

        delete jsonTest[key];
    }
});

score 0 · Answer 3 · answered Jun 06 '19 at 19:49

Try

json.map(x=> Object.keys(x).map(k=> x[k]===undefined ? delete x[k]:0));

let json=[{email: "1234569@hhh.pt", first: "Joao", last: "Bastos", gender: "Male", phone: "3.51939e+11"},
      {email: "", first: undefined, last: undefined, gender: undefined, phone: undefined}, 
      ];
      
json.map(x=> Object.keys(x).map(k=> x[k]===undefined ? delete x[k]:0)); 

console.log(json);

Remove undefined keys from json array

3 Answers3