Using the prototype makes for faster object creation, since that function does not have to be re-created each time a new object is created.
When you do this:
function animal(){
this.name = 'rover';
this.set_name = function(name){
this.name = name;
}
}
The set_name
function is created de novo each and every time you create an animal. But when you do this
animal.prototype.set_name = function(name){
this.name = name;
}
The function does not have to be re-created each time; it exists in one place in the prototype. So when you call someAnimal.set_name("Ubu");
the this
context will be set to someAnimal
and (the one and only) set_name
function will be called.
There is one advantage to using the first syntax though: functions created in this manner will have access to private data:
function animal(){
var privateData = 'foo'
this.name = 'rover';
this.set_name = function(name){
this.name = name;
alert(privateData); //will alert 'foo'
}
}
Douglas Crockford calls functions created like this "privileged" for that reason: they have access to both public, and private data.
0
Created by Adam Rackis on 2020-03-19 22:53:06 +0000 UTC
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