No colon after property name in object declaration, is it valid? [duplicate]

Answer 1

This is ES6 / ES2015 syntactic sugar (Property shorthand). With ES6:

const obj = {
    a(b) { 
        // Shorthand method
        // `this` context is `obj`
    },
    c
};

is equal to

var obj = {
    a: function a(b) {

    },
    c: c
};