Javascript Introduction

Simple example for javascript

1. Open notepad save file as index.html

2. Add below code.

<script>
    alert (“Hello!! This is JavaScript alert.”);
</script>




3. Open file with any browser. you will see below

4. The way in which we access data from textbox,same thing is applicable for list box and other input controls.

   1. Open notepad save file as index.html

   2. Add below code.

<script>
    function validateFormData(){
        var uname=document.loginForm.username.value;
        alert("uname >>"+ document.loginForm.username.value);
    }
</script>
    <form name="loginForm">
        User Name : <input type="text" name="username"></br>
        Password : <input type="text" name="password"></br>
   <input type="button" onclick="validateFormData()" value="Submit"></br>
   </form>

Here, we have accessed data from textbox into our function, so now we can easily validate this value as shown below.

Just modify the function as given below.

<script>
function validateFormData(){
    var uname = document.loginForm.username.value;
    alert("uname >> "+ uname);
    if(uname==''){
        alert("Blank, please correct.");
    }else{
        alert("correct");
    }
}
</script>

If textbox is empty and we click on Validate button then we will see an alert as below: