# createVector error : Cannot set properties of undefined
**URL:** https://discourse.processing.org/t/createvector-error-cannot-set-properties-of-undefined/34702
**Category:** Coding Questions
**Created:** [January 18, 2022, 1:31am UTC](https://discourse.processing.org/t/createvector-error-cannot-set-properties-of-undefined/34702 "2022-01-18T01:31:47Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Ruimao96](https://discourse.processing.org/u/Ruimao96)
#### Post date: [January 18, 2022, 1:31am UTC](https://discourse.processing.org/t/createvector-error-cannot-set-properties-of-undefined/34702/1 "2022-01-18T01:31:47Z")
a really simple script trying to use createvector to make a sliding box.
let b;
function setup() {
createCanvas(800, 800);
b=new box();
b.startp(200,500,400,700)
b.slided(20,100,40,80)
}
function draw() {
background(220);
b.slidem(0.1);
b.drawb();
b.resetr(500);
}
class box{
construator(){
this.org1=createVector(0,0);
this.org2=createVector(0,0);
this.dir1=createVector(0,0);
this.dir2=createVector(0,0);
this.pos1=createVector(0,0);
this.pos2=createVector(0,0);
}
startp(x,y,xx,yy){
this.org1.x= x;
this.org1.y= y;
this.org2.x= xx;
this.org2.y= yy;
}
slided(x,y,xx,yy){
this.dir1.x=x;
this.dir1.y=y;
this.dir2.x=xx;
this.dir2.y=yy;
}
slidem(x){
this.pos1.x += x_this.dir1.x;
this.pos1.y += x_this.dir1.y;
this.pos2.x += x_this.dir2.x;
this.pos2.y += x_this.dir2.y;
}
drawb(){
beginShape()
vertex(this.org1.x+this.pos1.x,this.org1.y+this.pos1.y);
vertex(this.org1.x+this.pos1.x+this.dir1.x,this.org1.y+this.pos1.y+this.dir1.y);
vertex(this.org2.x+this.pos2.x+this.dir2.x,this.org2.y+this.pos2.y+this.dir2.y);
vertex(this.org2.x+this.pos2.x,this.org2.y+this.pos2.y);
}
resetr(x){
if(pow(this.pos1.x,2)+pow(this.pos1.y,2)\>pow(x,2)){
this.pos1.x=0;
this.pos1.y=0;
this.pos2.x=0;
this.pos2.y=0;
}
}
}
p5js always says
TypeError: Cannot read properties of undefined (reading ‘x’) at box.slidem (/sketch.js:43:10) at draw (/sketch.js:11:5) at p5.\_main.default.redraw
in every line that trying to read the x or y value out of any vector, like
this.org1.x= x;
this.dir1.x=x;
this.pos1.x += x\*this.dir1.x;
vertex(this.org1.x+this.pos1.x,this.org1.y+this.pos1.y);
and i do not understand why. I spent 3 hours try to make simpler versions of this, and they all worked, so I supposed the way I use these function is correct. I just dont see any mistake I could make here. It almost seems like a bug.
---
### Author:  [@Metamoar](https://discourse.processing.org/u/Metamoar)
#### Post date: [January 18, 2022, 2:46am UTC](https://discourse.processing.org/t/createvector-error-cannot-set-properties-of-undefined/34702/2 "2022-01-18T02:46:39Z")
Looks like there are a few typos:
```auto
class box{
construator()
```
should be `constructor()`. After that, you’ll get another error where you’ll need to change `xthis.dir1.x` to `this.dir1.x` and the same for the other `xthis` in that method. Finally, you’ll need to add `endShape()` at the end of `drawb` in order to close the shape (or you won’t see anything)
---
### Author:  [@Ruimao96](https://discourse.processing.org/u/Ruimao96)
#### Post date: [January 18, 2022, 3:18am UTC](https://discourse.processing.org/t/createvector-error-cannot-set-properties-of-undefined/34702/3 "2022-01-18T03:18:35Z")
that works, thank you so much. i am surprised that p5js did not recognize default function typos like processing does.