how to conditionally create a member inside an object in javascript?

Question

how to conditionally create a member inside an object in javascript?

i was seeking for a solution like this in stackoverflow and in google but this is the idea

   a = {
  b: (conditionB? 5 : undefined),
  c: (conditionC? 5 : undefined),
  d: (conditionD? 5 : undefined),
  e: (conditionE? 5 : undefined),
  f: (conditionF? 5 : undefined),
  g: (conditionG? 5 : undefined),
 };

but i dont understand this... it doesnt work in nodejs i want to create an object a with many objects inside but if that objects are in the form send by the client

javascript
node.js
express

Answer 1

maybe what you want can be done using the array index notation?

a= {};
if(bla) a.b = "go";

Answer 2

Try this:

var a = {};
if(conditionB) {
   a['b'] = 5;
}

or

if(conditionB) {
   a.b = 5;
}

Answer 3

This can be achieved in 2 ways.

Either you use an if sentence for each conditional property as such:

    var a = {};
    if(conditionb){
      a.b = 5;
    }

Or if you don't want to create an if sentence for every property then you assign properties using the notation you presented in the question and then remove unnecessary ones in a loop:

    a = {
      b: (conditionB? 5 : undefined),
      c: (conditionC? 5 : undefined),
      d: (conditionD? 5 : undefined),
      e: (conditionE? 5 : undefined),
      f: (conditionF? 5 : undefined),
      g: (conditionG? 5 : undefined),
    };
    for(var i in a){
      if(a[i] === undefined){
        delete a[i];
      }
    }

Answer 4

You Can try this,

var dog = d;

var myObject = {};
myObject['a']=(1<2)? 1 : 2;
myObject['b']=(1<2)? 1 : 2;
myObject['c']=(1<2)? 1 : 2;
myObject[dog]=(1<2)? 1 : 2;

Just in case you are creating the properties dynamically.