const list = [1+2, 1*2, 1/2];
    console.log(list);                  // [ 3, 2, 0.5 ]
        

    let a = [1, 2, "3"]
    a = a.filter((a, i) => a === Number(i))
    console.log(a)                             # []
        

    /* using for-in loop */
    for (const prop in obj) {
        if (obj.hasOwnProperty(prop)) {
            console.log(prop, obj[prop]);
        }
    }


    /* using Object.keys() - introduced in ES6 */
    Object.keys(obj).forEach((prop, index)=>{
        console.log(prop, obj[prop]);
    });


    /* using Object.values() - introduced in ES8 */
    Object.values(obj).forEach((value)=>{
        console.log(value);
    });


    /* using Object.entries() - introduced in ES8 */
    Object.entries(obj).forEach((entry)=>{
        console.log(entry[0], entry[1]);
    });