use input javascript code example

Example 1: user input through js

var at = document.getElementById("email").value.indexOf("@");
var age = document.getElementById("age").value;
var fname = document.getElementById("fname").value;
submitOK = "true";

if (fname.length > 10) {
  alert("The name may have no more than 10 characters");
  submitOK = "false";
}

if (isNaN(age) || age < 1 || age > 100) {
  alert("The age must be a number between 1 and 100");
  submitOK = "false";
}

if (at == -1) {
  alert("Not a valid e-mail!");
  submitOK = "false";
}

if (submitOK == "false") {
  return false;
}

Example 2: input in javascript

Input Text Object
The Input Text object represents an HTML <input> element with type="text".

Access an Input Text Object
You can access an <input> element with type="text" by using getElementById():

Example
var x = document.getElementById("myText");
Tip: You can also access <input type="text"> by searching through the elements collection of a form.

Create an Input Text Object
You can create an <input> element with type="text" by using the document.createElement() method:

Example
var x = document.createElement("INPUT");
x.setAttribute("type", "text");