jq 當遇到如 ie left=auto 時的處理方式

cur: function() {
        debugger;
        if ( this.elem[ this.prop ] != null && (!this.elem.style || this.elem.style[ this.prop ] == null) ) {
            return this.elem[ this.prop ];
        }

        var parsed,
            r = jQuery.css( this.elem, this.prop );
        // Empty strings, null, undefined and "auto" are converted to 0,
        // complex values such as "rotate(1rad)" are returned as is,
        // simple values such as "10px" are parsed to Float.
        return isNaN( parsed = parseFloat( r ) ) ? !r || r === "auto" ? 0 : r : parsed;
    }