shallow-freeze.js

// Shallow freeze
Object.freeze(state);

// This will not work
state.twitter = '@zuck';

// Look, it's still @JamesJefferyUK
console.log(state.twitter);

// But this works because we're modifying a reference value (an object)
state.tweets[3] = 'I Love Facebook!';

// I Love Facebook!
console.log(state.tweets[3]);