Let's say we have two constructors like these:
function Player(x, y) {
this.x = x;
this.y = y;
this.hello = function() {
console.log("Hello, " + this.npc); // World npc property
}
}
function World() {
this.player = new Player(0, 0);
this.npc = "villager";
}
How can i access the npc property of World from the hello function in Player?
this doesn't work, since World is not a prototype of Player.
Use call. When used, it will allow you to bind the this context from World to the called hello function in Player.
function Player(x, y) {
this.x = x;
this.y = y;
this.hello = function() {
alert("Hello, " + this.npc); // World npc property
}
}
function World() {
this.player = new Player(0, 0);
this.npc = "villager";
this.player.hello.call(this);
}
new World();
world.player.hello.call(world). Or you could internalize the hello function call to world since it doesn't have much to do with player. You could have hello expect to take a world object. You could have World inherit the prototype of player and implement its own hello function. There are many options, the one which requires the least amount of change is using call.You have to instantiate the World function to make it an object as so:
var world = new World();
alert(world.npc);
Pass it as a parameter:
function Player(x, y) {
this.x = x;
this.y = y;
this.hello = function(npc) {
console.log("Hello, " + npc); // World npc property
}
}
function World() {
this.npc = "villager";
this.player = new Player(0, 0);
this.player.hello(this.npc);
}
Player constructor?var World = function () {
this.npc = "villager";
this.player = new Player(0, 0);
return {
npc: this.npc,
player: this.player
};
}();
You can now access the npc from other contexts using World.npc.
hellowho it's greeting. Pass it in as a param.