It can be as simple as that:
const sumValues = obj => Object.values(obj).reduce((a, b) => a + b);
Quoting MDN:
The
Object.values()
method returns an array of a given object’s own enumerable property values, in the same order as that provided by afor...in
loop (the difference being that a for-in loop enumerates properties in the prototype chain as well).
The
reduce()
method applies a function against an accumulator and each value of the array (from left-to-right) to reduce it to a single value.
from Array.prototype.reduce()
on MDN
You can use this function like that:
sumValues({a: 4, b: 6, c: -5, d: 0}); // gives 5
Note that this code uses some ECMAScript features which are not supported by some older browsers (like IE). You might need to use Babel to compile your code.