There are already a lot of cool features in ES6/ES7 for defining Javascript objects. However, the following pattern is common in Javascript:
const obj = {
requiredKey1: ...,
requiredKey2: ...
};
if (someCondition) {
obj.optionalKey1 = ...;
}
Is there a way to define the object all at once with both optional and required keys?
You can use object spread to have an optional property:
let flag1 = true;
let flag2 = false;
const obj = {
requiredKey1: 1,
requiredKey2: 2,
...(flag1 && { optionalKey1: 5 }),
...(flag2 && { optionalKey2: 6, optionalKey3: 7 }),
...(flag1 && { optionalKey4: 8, optionalKey5: 9 })
};
console.log(obj);To indicate optional key, you can assign to it null, if the condition is false
const someCondition = true;
const obj = {
requiredKey1: 1,
requiredKey2: 2,
optionalKey1: someCondition ? 'optional' : null
};
console.log(obj);the following pattern is common in Javascript
It should not. Having many objects of different shapes can incur a performance penalty. Records should always contain the same keys. So just use
const obj = {
requiredKey1: …,
requiredKey2: …,
optionalKey1: someCondition ? … : undefined,
};