Which Runs Faster?

let a = {};
for(let i = 0; i < 19; i++) {
    a["a" + i] = i
}

let sum = 0;
for(let i = 0; i < 10000; i++) {
    for(const prop in a) {
        sum += a[prop];
    }
}
let a = {};
for(let i = 0; i < 19; i++) {
    a["a" + i] = i
}

let sum = 0;
for(let i = 0; i < 10000; i++) {
    for(const prop in a) {
        sum += a[prop];
    }
}
https://jsbench.me/w3ku47yq6u/1

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