//HTML

<input type="text" name="name" id="uniqueID" value="value" />

//JS

var nameValue = document.getElementById("uniqueID").value;

​

//Html

<form id="myForm" name="myForm">

    <input id="email" name="email" value="some@email.com" />

</form>

​

//JS

var x=document.forms["myForm"]["email"].value;

//html

<form id="myForm">

  <input type="text" name="name" placeholder="Name">

  <input type="email" name="email" placeholder="Email">

  <button type="button" onclick="getFormValues()">Get Values</button>

</form>

​

//js

function getFormValues() {

  var form = document.getElementById("myForm");

  var nameValue = form.elements["name"].value;

  var emailValue = form.elements["email"].value;

  console.log("Name: " + nameValue);

  console.log("Email: " + emailValue);

}

​

​