Javascript Constructors and Objects

Question

I need to have an edge object like that :

var edge={ coordinates:[],  name};

function edge(coordinates,name)
{
this.coordinates = coordinates;
this.name = name;
}

However when I initialize it, I get an error saying edge is not a constructor.

var a=new Array();

a[0]=0+move; a[1]=200;  
a[2]=0+move; a[3]=130;
var ed=new edge(a,"a");

Answer 1

You can only have one identifier named edge in the same scope. When that happens the last one that is assigned to overwrites the earlier one. Because of hoisting, the function declaration is being processed first (even though it appears second in the code) and then your object is overwriting that. So when you get to the line that attempts to use edge as a constructor, it has already been overwritten by an object. See more on hoisting here.

function edge(coordinates, name){
  this.coordinates = coordinates;
  this.name = name;
}

var move = 100; // dummy variable just to make your code work

// Array literal notation. Simpler than making new array and populating
// indexes separately
var a = [0 + move, 200, 0 + move, 130 ];

// Use function as constructor
var e1 = new edge(a, "a");

console.log(e1);