How to know if there's a value inside an array of object in javascript?

Question

I have this array of object:

[Object, Object]
 0: Object
    {
     date: ""
     number: undefined
    }
 1: Object
     {
      date: ""
      number: undefined
     }

It always said required if that value is not empty. Maybe someone can help me with much more knowledgeable about this.

Here's my code:

$(function(){

 var len = $('#groupContainer > div').length;
 var arr = [];

 for(var i=0; i < len; i++){

    var number = $('#number_' + [i + 1]);
    var date = $('#date_' + [i + 1]);

    console.log(number)

    var a = number.map(function(){
        return this.value;
    });

    var b = date.map(function(){
        return this.value;
    });

    var newObj = {number: a[0], date: b[0]}
    arr.push(newObj);
 }

 for(var c = 0; c < arr.length; c++)
 {
    var count = c + 1;
    var message ="";

    for(var d in arr[c])
    {
        if(arr[c].hasOwnProperty(d))
        {       
            if(arr[c][d] == "")
            {
                message = d + ' is required!';
            }
            message += message + "\n";
        }
    }
    alert('Group: ' + count + ' ' + message + '\n');
  }
});

Demo

I'm trying to find if the value inside an array of object is null or empty. If not empty it will not show the alertbox. — aldrin27
– aldrin27, Commented Oct 1, 2015 at 2:44
you need to check the entire object? or a specific property? — Jossef Harush Kadouri
– Jossef Harush Kadouri, Commented Oct 1, 2015 at 2:45
so you would consider this as null object {name:''} but this as not null {name:'abc'}, am i right? — Jossef Harush Kadouri
– Jossef Harush Kadouri, Commented Oct 1, 2015 at 2:48
what's the expected result for this object {name:'abc', id: null} ? — Jossef Harush Kadouri
– Jossef Harush Kadouri, Commented Oct 1, 2015 at 2:54

Jonathan Lonowski · Accepted Answer · 2015-10-01 03:13:02Z

1

The check on emptiness appears to work correctly. Both fields in "Group 1" have a value and its message doesn't mention either as "required."

Though, you have an issue with how the message is being built, reporting a single property at least twice:

"Group: 2 date is required!date is required!"

This is due to these modifications of message:

if(arr[c][d] == "")
{
    message = d + ' is required!';
}
message += message + "\n";

The first line modifying the message, by using the assignment operator (=), will discard any previous value that message may have held.

var message = "something previous"

message = 'property' + ' is required!';

console.log(message); // "property is required!"

The other line then duplicates the contents of message, appending it to itself:

// same as `message = message + message + "\n";`
message += message + "\n";

console.log(message); // "property is required!property is required!\n"

How you could revise this is to modify message only when an empty field is found and concatenate onto the previous value with what's being added.

if(arr[c][d] == "")
{
    message += d + ' is required!\n';
    //      ^ concatenate onto the previous `message` value
    //        including the `\n` here
}
// remove the other modification

http://jsfiddle.net/b60981ku/

edited Oct 1, 2015 at 3:13

answered Oct 1, 2015 at 3:02

Jonathan Lonowski

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3 Comments

aldrin27 Over a year ago

What if i don't want to show alertbox if not empty? But rather return true. And move to the next process?

Jonathan Lonowski Over a year ago

@aldrin27 You can test if message is still empty after the loop -- if (message) { alert(...); }. Or, use another variable with message and count, such as var anyEmpty = false;, that you only set to true when an empty field is found, and test based on it -- if (anyEmpty) { alert(...); }.

aldrin27 Over a year ago

Thank you so much sir. Just what I need.

choz · Accepted Answer · 2015-10-01 03:03:13Z

1

You can check whether the variable is null or empty by,

arr[c][d] == null || arr[c][d].length <= 0

If I am not mistaken what you're trying to achieve..

FIDDLE

answered Oct 1, 2015 at 3:03

choz

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Comments

Community · Accepted Answer · 2020-06-20 09:12:55Z

Use a Custom validation

From what i understand after our small comment dialog, you should implement a custom validation like the one in the following function

function isObjectNullOrEmpty(obj) {
    if (!obj) {
        return true;
    }

    var requiredKeys = ['name'];
    for (var i in requiredKeys) {
        var key = requiredKeys[i];
        var value = obj[key];
        if (value === undefined || value === null) {
            return true;
        }

        if ((typeof value === 'string' || value instanceof String) && !value.trim()) {
            return true
        }

    }

    return false;
}

http://jsfiddle.net/nknaftq3/

$(function () {

    var object1 = {
        name: ''
    };
    alert(JSON.stringify(object1) + ' \n\nresult : ' + isObjectNullOrEmpty(object1));

    
    var object2 = {
        name: 'asd'
    };
    alert(JSON.stringify(object2) + ' \n\nresult : ' + isObjectNullOrEmpty(object2));

});

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How to know if there's a value inside an array of object in javascript?

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Use a Custom validation

http://jsfiddle.net/nknaftq3/

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