How to create search bar in Javascript that checks to see if items matches the input?

Question

I am trying to make a search bar in Javascript, and it works only a little so far. It will checks to see if the a tags have the input value in it, but it also shows when it's found at the end of the word - e.g. c will match CSS and Javascript (because Javascript also has a c in it).

function myFunction() {
  var input, filter, ul, li, a, i;
  input = document.getElementById("mySearch");
  filter = input.value.toUpperCase();
  ul = document.getElementById("myMenu");
  li = ul.getElementsByTagName("li");
  for (i = 0; i < li.length; i++) {
    a = li[i].getElementsByTagName("a")[0];
    if (a.innerHTML.toUpperCase().indexOf(filter) > -1) {
      li[i].style.display = "";
    } else {
      li[i].style.display = "none";
    }
  }
}

body {
  font-family: Arial, Helvetica, sans-serif;
}

* {
  box-sizing: border-box;
}

.row {
  display: flex;
}

.left {
  flex: 35%;
  padding: 15px 0;
}

.left h2 {
  padding-left: 8px;
}

.right {
  flex: 65%;
  padding: 15px;
}

#mySearch {
  width: 100%;
  font-size: 18px;
  padding: 11px;
  border: 1px solid #ddd;
}

#myMenu {
  list-style-type: none;
  padding: 0;
  margin: 0;
}

#myMenu li a {
  padding: 12px;
  text-decoration: none;
  color: black;
  display: block
}

#myMenu li a:hover {
  background-color: #eee;
}

<h2>Search Menu</h2>
<p>Start to type for a specific category inside the search bar to "filter" the search options.</p>

<div class="row">
  <div class="left" style="background-color:#bbb;">
    <h2>Menu</h2>
    <input type="text" id="mySearch" onkeyup="myFunction()" placeholder="Search.." title="Type in a category">
    <ul id="myMenu">
      <li><a href="#">HTML</a></li>
      <li><a href="#">CSS</a></li>
      <li><a href="#">JavaScript</a></li>
      <li><a href="#">PHP</a></li>
      <li><a href="#">Python</a></li>
      <li><a href="#">jQuery</a></li>
      <li><a href="#">SQL</a></li>
      <li><a href="#">Bootstrap</a></li>
      <li><a href="#">Node.js</a></li>
    </ul>
  </div>
  
  <div class="right" style="background-color:#ddd;">
    <h2>Page Content</h2>
    <p>Start to type for a specific category inside the search bar to "filter" the search options.</p>
    <p>Some text..Some text..Some text..Some text..Some text..Some text..Some text..Some text..</p>
    <p>Some other text..Some text..Some text..Some text..Some text..Some text..Some text..Some text..</p>
    <p>Some text..</p>
  </div>
</div>

I have tried checking to make sure the index of the found value is less than the length of the value, but it only works once.

function myFunction() {
  var input, filter, ul, li, a, i;
  input = document.getElementById("mySearch");
  filter = input.value.toUpperCase();
  ul = document.getElementById("myMenu");
  li = ul.getElementsByTagName("li");
  for (i = 0; i < li.length; i++) {
    a = li[i].getElementsByTagName("a")[0];
    if (a.innerHTML.toUpperCase().indexOf(filter) > -1 && a.innerHTML.toUpperCase().indexOf(filter) < input.value.length) {
      li[i].style.display = "";
    } else {
      li[i].style.display = "none";
    }
  }
}

body {
  font-family: Arial, Helvetica, sans-serif;
}

* {
  box-sizing: border-box;
}

.row {
  display: flex;
}

.left {
  flex: 35%;
  padding: 15px 0;
}

.left h2 {
  padding-left: 8px;
}

.right {
  flex: 65%;
  padding: 15px;
}

#mySearch {
  width: 100%;
  font-size: 18px;
  padding: 11px;
  border: 1px solid #ddd;
}

#myMenu {
  list-style-type: none;
  padding: 0;
  margin: 0;
}

#myMenu li a {
  padding: 12px;
  text-decoration: none;
  color: black;
  display: block
}

#myMenu li a:hover {
  background-color: #eee;
}

<h2>Search Menu</h2>
<p>Start to type for a specific category inside the search bar to "filter" the search options.</p>

<div class="row">
  <div class="left" style="background-color:#bbb;">
    <h2>Menu</h2>
    <input type="text" id="mySearch" onkeyup="myFunction()" placeholder="Search.." title="Type in a category">
    <ul id="myMenu">
      <li><a href="#">HTML</a></li>
      <li><a href="#">CSS</a></li>
      <li><a href="#">JavaScript</a></li>
      <li><a href="#">PHP</a></li>
      <li><a href="#">Python</a></li>
      <li><a href="#">jQuery</a></li>
      <li><a href="#">SQL</a></li>
      <li><a href="#">Bootstrap</a></li>
      <li><a href="#">Node.js</a></li>
    </ul>
  </div>
  
  <div class="right" style="background-color:#ddd;">
    <h2>Page Content</h2>
    <p>Start to type for a specific category inside the search bar to "filter" the search options.</p>
    <p>Some text..Some text..Some text..Some text..Some text..Some text..Some text..Some text..</p>
    <p>Some other text..Some text..Some text..Some text..Some text..Some text..Some text..Some text..</p>
    <p>Some text..</p>
  </div>
</div>

Is there a way to do that?

Answer 1

Just change this

if (a.innerHTML.toUpperCase().indexOf(filter) > -1)

To this

if (a.innerHTML.toUpperCase().indexOf(filter) === 0)