"SelectAll" CheckBox in GridView using jQuery

Here is a way to do it:

/**
 * Register logic for "select all" check box and the group of check boxes 
 * for each data row.
 * 
 * @param {Object} chkAllSelector     jQuery selector to find the "select all" check box
 * @param {Object} chkItemSelector    jQuery selector to find the check boxes for all the rows
 */

function registerSelectAll(chkAllSelector, chkItemSelector) {
    //"select all" checkbox
    var checkAllBox = $(chkAllSelector);
    //checkbox for each row
    var checkItems = $(chkItemSelector);       
    
    //check/uncheck all rows if "select all" is clicked
 checkAllBox.bind("click", function(){
            checkItems.each(function(){
                this.checked = checkAllBox[0].checked;
                })
        });
        
    //uncheck "select all" if some rows are unchecked
 checkItems.bind("click", function(){
            if(this.checked === false) {
             checkAllBox[0].checked = false;                    
            }
     });                     
}

To use it:

registerSelectAll(".chkAllHeader input", ".chkItem input");