var obj = {
    "a": 1,
    "b": 2
};
var ret = o2a(obj);
// ret = [ [1, "a"], [2, "b"]]
function o2a(obj) {
    const arr = []
    for (const key in obj) {
        arr.push([obj[key],key])
    }
    console.log(arr);
    return arr
}