Javascript "Not a Constructor" Exception while creating objects

constructor, javascript, object, typeerror

Solution

The code as posted in the question cannot generate that error, because `Project` is not a user-defined function / valid constructor.

function x(a,b,c){}
new x(1,2,3);               // produces no errors

You've probably done something like this:

function Project(a,b,c) {}
Project = {};               // or possibly   Project = new Project
new Project(1,2,3);         // -> TypeError: Project is not a constructor

Variable declarations using `var` are hoisted and thus always evaluated before the rest of the code. So, this can also be causing issues:

function Project(){}
function localTest() {
    new Project(1,2,3); // `Project` points to the local variable,
                        // not the global constructor!

   //...some noise, causing you to forget that the `Project` constructor was used
    var Project = 1;    // Evaluated first
}

Problem

I am defining an object like this: ``` function Project(Attributes, ProjectWidth, ProjectHeight) { this.ProjectHeight = ProjectHeight; this.ProjectWidth = ProjectWidth; this.ProjectScale = this.GetProjectScale(); this.Attributes = Attributes; this.currentLayout = ''; this.CreateLayoutArray = function() {....} } ``` I then try to create an instance like this: ``` var newProj = new Project(a,b,c); ``` but this exception is thrown: ``` Project is not a constructor ``` What could be wrong? I googled around a lot, but I still can't figure out what I am doing wrong.

Original source