In Javascript, how to conditionally add a member to an object?
I think @InspiredJW did it with ES5, and as @trincot pointed out, using es6 is a better approach. But we can add a bit more sugar, by using the spread operator, and logical AND short circuit evaluation:
const a = {
...(someCondition && {b: 5})
}
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
).
const obj = {
...(condition) && {someprop: propvalue},
...otherprops
}
Live Demo:
const obj = {
...(true) && {someprop: 42},
...(false) && {nonprop: "foo"},
...({}) && {tricky: "hello"},
}
console.log(obj);
I suggest the following:
const a = {
...(someCondition? {b: 5}: {})
}