Succinct/concise syntax for 'optional' object keys in ES6/ES7?
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,};