How to add javascript in master page?

<script language="javascript" type="text/javascript">
    function CreateGridHeader(DataDiv, GridView1, HeaderDiv)
    {
        var DataDivObj = document.getElementById(DataDiv);
        var DataGridObj = document.getElementById(GridView1);
        var HeaderDivObj = document.getElementById(HeaderDiv);

        //********* Creating new table which contains the header row ***********
        var HeadertableObj = HeaderDivObj.appendChild(document.createElement('table'));

        DataDivObj.style.paddingTop = '0px';
        var DataDivWidth = DataDivObj.clientWidth;
        DataDivObj.style.width = '500px';

        //********** Setting the style of Header Div as per the Data Div ************
        HeaderDivObj.className = DataDivObj.className;
        HeaderDivObj.style.cssText = DataDivObj.style.cssText;
        //**** Making the Header Div scrollable. *****
        HeaderDivObj.style.overflow = 'auto';
        //*** Hiding the horizontal scroll bar of Header Div ****
        HeaderDivObj.style.overflowX = 'hidden';
        //**** Hiding the vertical scroll bar of Header Div ****
        HeaderDivObj.style.overflowY = 'hidden';
        HeaderDivObj.style.height = DataGridObj.rows[0].clientHeight + 'px';
        //**** Removing any border between Header Div and Data Div ****
        HeaderDivObj.style.borderBottomWidth = '0px';

        //********** Setting the style of Header Table as per the GridView ************
        HeadertableObj.className = DataGridObj.className;
        //**** Setting the Headertable css text as per the GridView css text
        HeadertableObj.style.cssText = DataGridObj.style.cssText;
        HeadertableObj.border = '1px';
        HeadertableObj.rules = 'all';
        HeadertableObj.cellPadding = DataGridObj.cellPadding;
        HeadertableObj.cellSpacing = DataGridObj.cellSpacing;

        //********** Creating the new header row **********
        var Row = HeadertableObj.insertRow(0);
        Row.className = DataGridObj.rows[0].className;
        Row.style.cssText = DataGridObj.rows[0].style.cssText;
        Row.style.fontWeight = 'bold';

        //******** This loop will create each header cell *********
        for(var iCntr =0; iCntr < DataGridObj.rows[0].cells.length; iCntr++)
        {
            var spanTag = Row.appendChild(document.createElement('td'));
            spanTag.innerHTML = DataGridObj.rows[0].cells[iCntr].innerHTML;
            var width = 0;
            //****** Setting the width of Header Cell **********
            if(spanTag.clientWidth > DataGridObj.rows[1].cells[iCntr].clientWidth)
            {
                width = spanTag.clientWidth;
            }
            else
            {
                width = DataGridObj.rows[1].cells[iCntr].clientWidth;
            }
            if(iCntr<=DataGridObj.rows[0].cells.length-2)
            {
                spanTag.style.width = width + 'px';
            }
            else
            {
                spanTag.style.width = width + 20 + 'px';
            }
            DataGridObj.rows[1].cells[iCntr].style.width = width + 'px';
        }
        var tableWidth = DataGridObj.clientWidth;
        //********* Hidding the original header of GridView *******
        DataGridObj.rows[0].style.display = 'none';
        //********* Setting the same width of all the componets **********
        HeaderDivObj.style.width = DataDivWidth + 'px';
        DataDivObj.style.width = DataDivWidth + 'px';
        DataGridObj.style.width = tableWidth + 'px';
        HeadertableObj.style.width = tableWidth + 20 + 'px';
        return false;
    }

    function Onscrollfnction()
    {
        var div = document.getElementById('DataDiv');
        var div2= document.getElementById('HeaderDiv');
        //****** Scrolling HeaderDiv along with DataDiv ******
        div2.scrollLeft = div.scrollLeft;
        return false;
    }

    </script>