$(document).ready(function() {
$('#selecctall').click(function() {  //on click
    if(this.checked) { // check select status
        $('.checkbox1').each(function() { //loop through each checkbox
            this.checked = true;  //select all checkboxes with class "checkbox1"
        });
    }else{
        $('.checkbox1').each(function() { //loop through each checkbox
            this.checked = false; //deselect all checkboxes with class "checkbox1"
        });
    }
});

});

<ul class="chk-container">
  <li><input type="checkbox" id="selecctall"/> Selecct All</li>
  <li><input class="checkbox1" type="checkbox" name="check[]" value="item1"> This is   Item 1</li>
  <li><input class="checkbox1" type="checkbox" name="check[]" value="item2"> This is Item 2</li>
  <li><input class="checkbox1" type="checkbox" name="check[]" value="item3"> This is Item 3</li>
  <li><input class="checkbox1" type="checkbox" name="check[]" value="item4"> This is Item 4</li>
</ul>

$('#selecctall').click(function() {

$('#selecctall').click(function(event) {

$('#selecctall').click(function(foo) {

$('#selecctall').click(function(foo, bar, baz, bing) {