Make javascript variable can be empty

Question

Hi i have this function below that removes duplicates from the variable suggest but sometimes the data i receive for the suggest variable is empty and the code below wont work beacause of the JSON.parse function how do i make it so that the variable accepts empty data so that the code below will still run without any problems. Any help would be appreciated thanks!

function suggestData(data){

    var suggest = []; // I tried adding this and setting it to null but it doesn't seem to work.
    suggest = JSON.parse(data);

    for (var i = suggest.length - 1; i >= 0; i--) { 
        for (var j = 0; j < arrString.length; j++) {
            if (suggest[i] === arrString[j]) {
                suggest.splice(i, 1);
            }
        }
    }

So you want to check if data-parameter has value? Did you try finding it on Google or this site, there are numerous answers for that. — Esko
– Esko, Commented Jun 8, 2018 at 7:29

Akshat · Accepted Answer · 2018-06-08 07:50:57Z

1

You can set suggest inside an if condition to check whether data exists or not

function suggestData(data){

    var suggest = [];

    if(data){
       suggest = JSON.parse(data);
    }

    for (var i = suggest.length - 1; i >= 0; i--) { 
        for (var j = 0; j < arrString.length; j++) {
            if (suggest[i] === arrString[j]) {
                suggest.splice(i, 1);
            }
        }
    }

Also you can simply end the function if you do not want to execute it when data is empty:

function suggestData(data) {
   if(!data){
      return false;
    }
  //other code here
  ...
}

answered Jun 8, 2018 at 7:50

Akshat

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Comments

Ankit Agarwal · Accepted Answer · 2018-06-08 07:29:51Z

1

Set the length conditionally as,

var length = suggest? suggest.length: 0;

function suggestData(data){

    var suggest = [];
    suggest = JSON.parse(data);
    var length = suggest? suggest.length: 0;
    for (var i = length - 1; i >= 0; i--) { 
        for (var j = 0; j < arrString.length; j++) {
            if (suggest[i] === arrString[j]) {
                suggest.splice(i, 1);
            }
        }
    }
}
suggestData(null);

answered Jun 8, 2018 at 7:29

Ankit Agarwal

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3 Comments

Best Jeanist Over a year ago

actually i want to make it so that it can JSON.parse a empty string

Ankit Agarwal Over a year ago

@Bobby I did not get that. What do you mean?

Best Jeanist Over a year ago

Because this error keeps poping up SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data so im thinking that it cant run because the suggest is empty. So what i want to is to try to make the JSON.parse be able to parse a empty string

Kshitiz singhal · Accepted Answer · 2018-06-08 07:32:12Z

1

function suggestData(data){

var suggest = []; // I tried adding this and setting it to null but it doesn't seem to work.

if(data) suggest = JSON.parse(data);

for (var i = suggest.length - 1; i >= 0; i--) { 
    for (var j = 0; j < arrString.length; j++) {
        if (suggest[i] === arrString[j]) {
            suggest.splice(i, 1);
        }
    }
}

Just add the if condition on parsing line like written in above code::

if(data) suggest = JSON.parse(data);

answered Jun 8, 2018 at 7:32

Kshitiz singhal

143 bronze badges

Comments

Attersson · Accepted Answer · 2018-06-08 07:59:07Z

1

The simplest:

if(!data || !suggest)
    return;

edited Jun 8, 2018 at 7:59

answered Jun 8, 2018 at 7:34

Attersson

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Comments

Isaac · Accepted Answer · 2018-06-08 07:31:28Z

0

let array = [1,2,3,8,3,4,4,5]
const removeDuplicateItems = arr => [...new Set(arr)];

console.log(removeDuplicateItems(array))

If you just want to remove duplicated items in an array, you can instead try Set which is quite handy

Even if array is empty or null, this method removeDuplicateItems will still works

answered Jun 8, 2018 at 7:31

Isaac

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1 Comment

Isaac Over a year ago

@downvoters: How is suggesting another way is consider a bad answer?

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