Use getElementsByName() method t0 get get element by name in JavaScript. This method returns a NodeList of elements. Because it’s plural in this method.
That returns an array of elements, so use [0] to get the first occurrence.
document.getElementsByName("name")[0].valueExample of How to JavaScript get element by name
If looking for a single element, take the first one from the nodelist, for example here is complete HTML code:
<!DOCTYPE html>
<html>
<body>
    Name: <input name="fname" type="text" value="John"><br>
    <button onclick="myFunction()"> Get Element</button>
    <p id="demo"></p>
    <script>
        function myFunction() {
          var x = document.getElementsByName("fname")[0].tagName;
          
          document.getElementById("demo").innerHTML = x;
      }
  </script>
</body>
</html>Output:

Do comment if you have any questions or doubts or suggestions on this topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version