Is there anything like this in JavaScript? Basically, I'm looking for something along these lines:
let obj_a = {test: "one", property: "two"};
let obj_b = {test: "1", other: "three"};
let obj_b ...= obj_a; // would be the equivalent of obj_b = {...obj_b, ...obj_a}
Is there builtin syntax for something like that, or is this the best I'm going to get in ES6?
Object.assign would do.
let obj_a = { test: "one", property: "two" },
obj_b = { test: "1", other: "three" };
Object.assign(obj_b, obj_a);
console.log(obj_b);I don't think any such syntax exists, but if you need to use something like that a lot, you could monkey-patch the Object class with a utility function for it:
Object.prototype.merge = function(x) { Object.assign(this, x) }
let obj_a = {test: "one", property: "two"};
obj_a.merge({test: "1", other: "three"});
console.log(obj_a);An other option is to use Object.assign it's not an operator but it get's the job done:
Object.assign(obj_b, obj_a)
// {test: 'one', other: 'three', property: 'two'}
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign