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javascriptprototype

Why can't I refer to the inherited method from JavaScript prototype within method

When I use JavaScript prototype to inherit a object and want to use it's method in the following way:

var Father = {
  name:'Father',
  act:function(){
    console.log('the name is '+this.name);
  }
}
var Son = function(){
   act();
}
Son.__proto__ = Father;
Son();

This doesn't work, when Js Engine run Son(), it should search act() through it's prototype chain.

But why it only works the following way:

var Father = {
  name:'Father',
  act:function(){
    console.log('the name is '+this.name);
  }
}
var Son = {
  name:'Son'
}
Son.__proto__=Father;
Son.act();

Solution

  • act is not any property of an object. it is just a variable that points to a function.

    When you try to access a property of an object then only Javascript first check if the property exists in that object or not, if it does not then only it search in its prototype until a prototype is null.