CODEWITHSUNDEEP
javascriptjson
user3278897
user3278897

Reputation: 1004

Java script json parse object : Not removing the "," after the delete operation

I am trying to convert string to the JS Object. It is successfully using the JSON.parse method, but the problem is, when we delete some thing from the object it is missing/not deleting the ",". Check this program and output:

var jsonString =    '[{"connectionName" : "conn1", "ipaddress" : "127.0.0.1","port" : "80"}, {"connectionName" : "conn2", "ipaddress" : "127.0.0.100","port" : "760"}]';

var a  = JSON.parse(jsonString); // Successfully converted to Object and i can access them

delete a[1]; //deletes the conn2

var obj = {"connectionName" : "conn3", "ipaddress" : "127.0.0.100","port" : "760"};

a.push(obj); 
console.dir(a);

Output:

[ { connectionName: 'conn1', ipaddress: '127.0.0.1', port: '80' },
  ,
  { connectionName: 'conn3',
    ipaddress: '127.0.0.100',
    port: '760' } ]

Can you observe that extra "," in between two objects: 

'80' },
      ,
      { connectionName:

Upvotes: 3

Views: 304

Answers (2)

James Choi
James Choi

Reputation: 1128

Use Array.prototype.splice(<index>, <numElements>, <newElements>) to replace a element in the array. 

var jsonString = '[{"connectionName" : "conn1", "ipaddress" : "127.0.0.1","port" : "80"}, {"connectionName" : "conn2", "ipaddress" : "127.0.0.100","port" : "760"}]';
var obj = {"connectionName" : "conn3", "ipaddress" : "127.0.0.100","port" : "760"};

var a  = JSON.parse(jsonString); 
a.splice(1, 1, obj);   // remove starting at index 1, 1 element, and insert obj



console.dir(a);

Notice how the original array a is modified without having to create a new variable. I used to use pop and push but found that splice is cleaner when you have multiple elements to insert/remove from the array.

var jsonString = '[{"connectionName" : "conn1", "ipaddress" : "127.0.0.1","port" : "80"}, {"connectionName" : "conn2", "ipaddress" : "127.0.0.100","port" : "760"}]';
var obj1 = {"connectionName" : "conn3", "ipaddress" : "127.0.0.100","port" : "760"};
var obj2 = {"connectionName" : "conn4", "ipaddress" : "127.0.0.100","port" : "760"};
var obj3 = {"connectionName" : "conn5", "ipaddress" : "127.0.0.100","port" : "760"};

var a  = JSON.parse(jsonString); 
a.splice(1, 1, obj1, obj2, obj3);   // remove starting at index 1, 1 element, and insert obj1, obj2, obj3



console.dir(a);

Upvotes: 1

Yury Tarabanko
Yury Tarabanko

Reputation: 45106

If you want to remove array item use splice instead of delete

a.splice(1, 1);

And just to be clear. splice will mutate the original array.

Upvotes: 3

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