array.forEach((x) => {

   x.r = x.a + x.b;

});

for(const x of array) {

    x.r = x.a + x.b;

}

const r = [];

for(const {a, b} of array) {

    r.push(a + b);

}

array.map(x => x.a + x.b)

array.map(({a,b}) => a + b)

const r = new Array(array.length);

for (let i = 0; i < array.length; ++i) {

   r[i] = array[i].a + array[i].b;

}

array.reduce((p, x) => p + x.a + x.b, 0);

array.reduce((p, {a,b}) => p + a + b, 0);

let r = 0;

for (const x of array) {

   r += x.a + x.b;

}

let r = 0;

for (const {a,b} of array) {

   r += a + b;

}

array.forEach((_, i) => {

   array[i].r = array[i].a + array[i].b;

});