replace Function.prototype does not work

[Stone Zhong]

Hi there,

I am reading the book "The Concise Guide to Dojo" and I saw some code
like below on page 11:

decafbad.school.PersonClassic.prototype = {...

I personally did a test like below

==== this code does not work ===
function Person(name) {
this.name = name;
Person.prototype = {
sayHi: function() { alert('hi ' + this.name); }
};
}
var a = new Person("JavaScript");
a.sayHi(); // I got error a.sayHi is not a function

however, if I change the code to below style , it worked,
function Person(name) {
this.name = name;
Person.prototype.sayHi = function() { alert('hi ' + this.name);
}
var a = new Person("JavaScript");
a.sayHi();

My conclusion is, a function's prototype already has some hidden
properties which might be important, replace function's prototype is
not good idea, only add property to function's prototype.

 

[David Mark]

Hi there,

I am reading the book "The Concise Guide to Dojo" and I saw some code
like below on page 11:

Best advice is to burn it.

decafbad.school.PersonClassic.prototype = {...
LOL.


I personally did a test like below

==== this code does not work ===
function Person(name) {
this.name = name;
Person.prototype = {
sayHi: function() { alert('hi ' + this.name); }
};

Too late to do that. The die is cast at this point.

}
var a = new Person("JavaScript");
a.sayHi(); // I got error a.sayHi is not a function

however, if I change the code to below style , it worked,
function Person(name) {
this.name = name;
Person.prototype.sayHi = function() { alert('hi ' + this.name);
}

function Person(name) {
this.name = name;
}

Person.prototype.sayHi = function() { alert('hi ' + this.name);

There is no reason to set that property on each construction.

var a = new Person("JavaScript");
a.sayHi();

My conclusion is, a function's prototype already has some hidden
properties which might be important, replace function's prototype is
not good idea, only add property to function's prototype.

Your conclusion is fine, but the observations that led you to it are faulty.

 

[Thomas 'PointedEars' Lahn]

Best advice is to burn it.

No, to recycle it. Burning it increases your carbon footprint, and it has
done enough damage already


SCNR

PointedEars