NodeEditor.html

<canvas id="nodeEditorCanvas" width="750" height="550" style="border:1px solid #000000;"/>

<script>
    var canvas = document.getElementById("nodeEditorCanvas");
    var ctx = canvas.getContext("2d");
    ctx.font="30px Arial";
    ctx.textAlign="center";

    function SetColor(color){
        ctx.fillStyle = color;
    }

    function DrawRect(x,y,sizeX,sizeY) {
        ctx.fillRect(x,y,x+sizeX,y+sizeY);
    }
    function DrawLine(fromX,fromY,toX,toY){
        ctx.moveTo(fromX,fromY);
        ctx.lineTo(toX,toY);
        ctx.stroke();
        ctx.moveTo(0,0);
    }
    function DrawCircle(x,y,radius){
        ctx.beginPath();
        ctx.arc(95,50,40,0,2*Math.PI);
        ctx.stroke();
        ctx.moveTo(0,0);
    }
    function DrawText(x,y,text){
        ctx.fillText(text,x,y);
    }
</script>

<script>
    SetColor("black");
    DrawRect(100,100,100,30);
    SetColor("red");
    DrawLine(100,100,200,130);

</script>