In Javascript, how would you make a variable read-only?

declaring a variable using const keyword. This declares a read-only named constant

There are few solutions, one is to use revealing modular pattern where you return function that only retrieves value of property, and everything is wrapped in closure. Other solution is to use Object.defineProperty where you cane be specific and set write value of object property.

There is no "const" keyword back in 2013 when the question was asked.

var obj = {}; Object.freeze(obj); // Or when defining a property Object.defineProperty(obj, 'key', { writable: false, value: 'read-only variable' });

This looks so good: bit.ly/faang100