Json object value by concatenating two variables

Question

I am trying to create a json which contains a key value pair where the value is generated based on a concatenation of another two variables(strings).

Apart from concatenating like,

var a = "A";
var b = "B";
var c = a+" "+b;

and using variable 'c' directly, is there a way to append variables within the key value as below.

var fName = "Test1";
var lName = "Test2";

var json = {"fname":fname,"lname":lName,"fullname":"'fName'+' '+'lname'"}

I expect to result {"fname":"Test1","lname":"Test2","fullname":"Test1 Test2"}

Please let me know if this is possible to achieve.

Take a look at: w3schools.com/jsref/jsref_join.asp

SPlatten
– SPlatten

2019-04-02 13:08:52 +00:00
Commented Apr 2, 2019 at 13:08 — SPlatten
– SPlatten, Commented Apr 2, 2019 at 13:08

AntonyG · Accepted Answer · 2019-04-03 23:32:57Z

1

var fName = "Test1";
var lName = "Test2";

var json = {"fname":fName,"lname":lName,"fullname": fName + " " + lName}

Edit: Following the comments, I'll illustrate other ways to play with JSON strings and objects...

// json is a JavaScript Object
typeof json  // -> "object"

// If you want to create JSON string representing it, use JSON.stringify()
var jsonString = JSON.stringify(json)

typeof jsonString  // -> "string"

// If you like pain, you can also build that string manually
// with the right escape sequences... (Do not do that)
var sillyJsonString = "{\"fname\":" + "\""+fName + "\",\"lname\":" + "\"" + lName + "\",\"fullname\":" + "\""+fName + " " + lName + "\"}"

typeof sillyJsonString  // -> "string"

// And now let's make sure they have the same content
jsonString === sillyJsonString  // -> true

// And the final part, re-create the object for JSON string
var sameJsonObject = JSON.parse(sillyJsonString)

// Now let's compare that the objects have the same content (but the are not equal ;))
JSON.stringify(json) === JSON.stringify(sameJsonObject)  // -> true

Hope this will point you in the right direction...

edited Apr 3, 2019 at 23:32

answered Apr 2, 2019 at 13:00

AntonyG

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6 Comments

Luke Over a year ago

I am passing effective json within double quotes as below. ``` "{"fname":fName,"lname":lName,"fullname": fName + " " + lName}" ``` Any escape character or any method to use this

AntonyG Over a year ago

What exactly are you trying to do? Do you want to parse some JSON? Create a JSON string? If you parse it, where do you take it from? What are these "triple single quote"?

Luke Over a year ago

Triple quotes added to format the code in comment. Ignore that please, Thank you for the clarification. I am trying to update json on the fly. Seems it's not possible. So I will create a new variable with merged values. Thanks for your support Antony.

AntonyG Over a year ago

What do you mean by on the fly? If json is an object, not a string (like in your original question), you can add properties to it: json["newKey"] = "newValue"

Luke Over a year ago

Apologies for the confusion. Json is a string in this case. It's a hassle and I am considering a different approach. Thanks

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