[Programming questions] rebuild binary tree

Subject description:

And enter the result in a preorder traversal of a binary tree in preorder traversal of the binary tree a rebuild. Suppose Results preorder traversal order and input of duplicate numbers are free. Before entering e.g. preorder traversal sequence {1,2,4,7,3,5,6,8} and {4,7,2,1,5,3,8,6} order traversal sequence, and the reconstructed binary tree return.
Code:

function reConstructBinaryTree(pre, vin)
{
    // write code here
    var result =null;
    if(pre.length>1){
        var root = pre[0];
        var vinRootIndex = vin.indexOf(root);
        var vinLeft = vin.slice(0,vinRootIndex);
        var vinRight = vin.slice(vinRootIndex+1,vin.length);
        pre.shift();
        var preLeft = pre.slice(0,vinLeft.length);
        var preRight = pre.slice(vinLeft.length,pre.length);
        result={
            val:root,
            left:reConstructBinaryTree(preLeft,vinLeft),
            right:reConstructBinaryTree(preRight,vinRight)
        }
       
    }else if(pre.length ===1){
        result= {
            val :pre[0],
            left:null,
            right:null
        }
    }
    return result;
}

Ideas: