JavaScript study notes: Extending the functions of types

JavaScript allows extending functionality to basic types. For example, you can add a method to Object.prototype to make the method available to all objects. This approach works equally well for functions, arrays, strings, numbers, regular expressions, and Boolean values.

For example, you can add a method to Function.prototype to make it available to all functions:

Function.prototype.method = function(name, func) {  this.prototype[name] = func;  return this;  
}

By adding a method method to Function.prototype, and then adding a method, you can directly call the method method without having to write a prototype. For example, JavaScript does not have an integer type. We can implement this by adding an integer method class to Number.prototype.

Number.method("integer", function(){    return Math[this < 0 ? &#39;ceil&#39; : &#39;&#39;floor&#39;](this);
});
console.log((-10 / 3).integer());   //out put -3

By adding methods to basic types, the expressiveness of the language can be greatly improved. Because of the dynamic nature of JavaScript prototypal inheritance, the new method is immediately assigned to all object instances, including objects that were created before the method was added.

Since the prototype of the basic type is a public structure, you must be careful when using the class library. A safe bet is to only add the method if you are sure it does not exist, for example:

Function.prototype.method = function(name, func) {  if (!this.prototype(name)) {    this.prototype[name] = func;
  }  return this;
};