How to Click or trigger <a href="javascript:viewPage('ABC');> with DOM - function

Question

I'm a beginner, tried to click the link with DOM but didn't worked. how can I click or trigger the function? and why didn't that work?
<li id="viewPage">viewPage
document.getElementById("viewPage").click()
function viewPage(Name,Number){
$("#ViewPage li").removeClass("active");
$("#"+Name).addClass("active");
$("#ViewPage").load(
Name+".asp",
{
Number : Number
},
function( response, status, xhr ) {
if ( status == "error" ) {
var msg = "there was an error: ";
$( "#error" ).html( msg + xhr.status + " " + xhr.statusText );
}
});
}

Answer 1

Since you don't seem to mind using jquery in the rest of your code, here is an easy way to get the click using jquery:
$('#viewPage').click(function() {
console.log('Now your click function is working');
});
function viewPage1(Name, Number) {
$("#ViewPage1 li").removeClass("active");
$("#" + Name).addClass("active");
$("#ViewPage1").load(
Name + ".asp", {
Number: Number
},
function(response, status, xhr) {
if (status == "error") {
var msg = "there was an error: ";
$("#error").html(msg + xhr.status + " " + xhr.statusText);
}
});
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<li id="viewPage">viewPage1