JavaScript - Pasar un valor css al javascript

<img src='img1.jpg' id='img1' style='left:40%'>

<script>

var obj=document.getElementById('img1').style.left;

confirm(' Posición: ' + obj);

</script>

<script>

SetTimeout(fuction mymove(){

Var elem=document.getElementById("imglogo");

Var

pos=document.getElementById("imglogo").style.left;

Var id=setInterval(frame,200);

Fuction frame(){

If(pos==10){

ClearInterval(id);}

Else{

Pos--;

Elem.style.left=pos +'%';

}

}

},2000)

</script>

pos = parseInt(document.getElementById("imglogo").style.left);