In JavaScript, how to conditionally add a member to an object?
javascript
Solution
In pure Javascript, I cannot think of anything more idiomatic than your first code snippet.
If, however, using the jQuery library is not out of the question, then $.extend() should meet your requirements because, as the documentation says:
Undefined properties are not copied.
Therefore, you can write:
var a = $.extend({}, {
b: conditionB ? 5 : undefined,
c: conditionC ? 5 : undefined,
// and so on...
});
And obtain the results you expect (if `conditionB` is `false`, then `b` will not exist in `a`).
Problem
I would like to create an object with a member added conditionally. The simple approach is: ``` var a = {}; if (someCondition) a.b = 5; ``` Now, I would like to write a more idiomatic code. I am trying: ``` a = { b: (someCondition? 5 : undefined) }; ``` But now, `b` is a member of `a` whose value is `undefined`. This is not the desired result. Is there a handy solution? Update I seek for a solution that could handle the general case with several members. ``` 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), }; ```