SOURCE

var NormalFrog = function() {
  this.name = '青蛙';
  this.legs = 4;
};

NormalFrog.prototype.sayHi = function() {
  console.log('呱呱呱~ ' + this.name + '有' + this.legs + '条腿');
};

var WeirdFrog = function() { };
WeirdFrog.prototype = Object.assign({ }, NormalFrog.prototype, {
	legs: 8,
  name: '外星青蛙'
});

var frog1 = new NormalFrog();
frog1.sayHi();

var frog2 = new WeirdFrog();
frog2.sayHi();

frog2.legs = 100;
frog2.sayHi();

frog1.sayHi();