SOURCE

function fromEntries(arr) {
    let obj = {};
    for(let i = 0; i < arr.length; i++) {
        let value = arr[i];
        obj[value[0]] = value[1];
    }
    return obj;
}

let arr=[["first", 1], ["second",2]];
obj2 = fromEntries(arr)
console.log(obj2.first)
console.log(obj2.second)