function funct1()
{
//have this function do what ever you want it to do

}

function funct2()
{
//same here with function 2

}

function callAboveFunctions()
{
funct1();
funct2();

}

In your html <a href="javascript:callAboveFunctions();">Click here to trigger the 2 fonctions</a>

<script>
function func1() {
  //.....
}

function func2() {
  //.....
}

function doUpdate() {
  func1();
  func2();
}
</script>

<input type="text" name="myTextbox" onClick="doUpdate();" onChange="doUpdate();">

<script>
function doOneThing() {
  //.....
}

function doAnotherThing() {
  //.....
}

function doUpdate() {
  doOneThing();
  doAnotherThing();
}
</script>

<input type="text" name="myTextbox" onClick="doUpdate();">