Get HTML tag values with Javascript
In this article you will learn Javascript interaction with HTML. Throughout this article you will get following question’s answers.
What is Javascript?
What is use of Javascript (JS)?
How to enable Javascript?
How to comment in javascript?
Why javascript validation (client side) required?
How to pass the parameter into javascript function?
How to get and set HTML element value in javascript?
<p>, <div> and <input type=”????”/>
Sample Member Form
What is Javascript?
Javascript is weakly typed, object oriented and dynamic language. Its lightweight and all modern browser built in javascript engine.
JS is shortcut / short name of Javascript.
What is use of Javascript (Js) ?
Js is used for interacting and manipulation with DOM (Document Object Model) elements. Js mostly used for interaction with client side object. You can get and set the value of DOM object. Beauty of JS is there is no addition plugin or extension required to implement or uses for JS.
How to enable Javascript?
Mostly in <head> section or other section of html or web document just write <script> tag, javascript is ready to use. Nowadays visual studio also provide intellisense for javascript (js).
Example:
<html>
<head>
<script type="text/javascript">
//commenting single line
/* Multi line comment.
document.write("this will not execute.")
document.write("this will not execute.")
*/
</script>
<script>
//Javascript can also run only writing SCRIPT tag.
</script>
</head>
<body>
</body>
</html>
You can start coding in javascript by just adding <script> tag or <script type=”text/javascript”>
How to comment in javascript?
Majority all languages having two types of comments:
1. Single line comment.
2. Multi-line comment.
1. Single line comment: This will comment your single line of code with help of //
Two forward slash.
Example:
//Javascript can also run only writing SCRIPT tag.
2. Multi-line comment: This will comment your multi-line of code with help of /* */
Two forward slash.
/* Multi line comment.
document.write("this will not execute.")
document.write("this will not execute.")
*/
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Why javascript validation (client side) required?
Javascript(js) is client side scripting language which run on client browser. (those things run on user browser that called CLIENT SIDE). Using client side validation that reduce load on server side and reduce unnecessary round-trip.
You can validate all types of DOM object with javascript.
Example:
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Above can validate with javascript clientside with following points.
Name field textbox: 1. User entered or not in textbox.
2. Can put restriction only alphabet characters allowed in textbox.
3. Minimum Length requirement.
Mobile field textbox: 1. User entered or not in textbox.
2. Can put restriction only numeric character allowed in textbox.
3. Minimum length requirement.
Birth-Date field textbox: 1.Valid date entered or not in textbox.
2.Date format restriction.
Gender dropdownlist: 1. User selected or not.
2. Hide or display item.
How to pass the parameter into javascript function?
Parameter is value which useful inside the function to do the processing. Passing the parameter(s) to javascript function is very simple. In sample code your will come to know.
Function without Parameter
Syntax:
function <function name>
{
}
Example:
function setclass()
{
}
Function with Parameter
Syntax:
function <function name>(parameter1 , parameter2 . .. . .)
{
}
Example:
function SumVal(val1, val2)
{
return val1 + val2 ;
}
How to get and set HTML element value in javascript?
<h1>, <p>, <div> and other content tag
To change contents of H1, P and DIV and content tags can be possible through (innerText, innerHtml).
innerText : To get and set change text of element.
innerHTML: To get and set change text of element.
NOTE:
My suggestion content elements content (inner text) can be get/set with help of INNERTEXT , INNERHTML.
FORM control element value can be get/set with help of VALUE.
Change the content of <H1> tag: In this we are going to change the contents of <H1> tag with help of innerText of javascript.
<h1 id="title">Welcome To Tutorials</h1>
To get Value of H1 Tag:
Alert(document.getElementById("title").innerText);
To set Value of H1 Tag:
document.getElementById("title").innerText = "Welcome to Javascript";
We had called click event of button, go through sample code.
CODE:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Sum Example</title>
<script type="text/javascript">
function CalcAdd() {
document.getElementById("title").innerText = "Welcome to Javascript";
}
</script>
</head>
<body>
<h1 id="title">Welcome To Tutorials</h1>
<br/>
<br/>
<input type="button" name="clickbtn" value="On Click Title Will Change" onClick="CalcAdd()"/>
</body>
</html>
OUTPUT:
ON LOAD VIEW:
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AFTER CLICKED ON BUTTON
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Change the content of <P> tag: In this we are going to change the contents of <P> tag with help of innerHTML of javascript.
<p id="para">First paragraph element of page.</p>
document.getElementById("para").innerHTML = "<b><i>Updated value of first paragraph </i></b>";
CODE:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>P Tag Example</title>
<script type="text/javascript">
function CalcAdd() {
//to set the P tag contents
document.getElementById("para").innerHTML = "<b><i>Updated value of first paragraph </i></b>";
}
</script>
</head>
<body>
<p id="para">First paragraph element of page.</p>
<br />
<br />
<input type="button" name="clickbtn" value="On Click Title Will Change" onClick="CalcAdd()" />
</body>
</html>
OUTPUT:
ON LOAD VIEW:
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AFTER CLICKED ON BUTTON
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Change the content of <div> tag: In this we are going to change the contents of <P> tag with help of innerHTML of javascript.
<p id="para">First paragraph element of page.</p>
document.getElementById("para").innerHTML = "<b><i>Updated value of first paragraph </i></b>";
OUTPUT:
ON LOAD VIEW:
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AFTER CLICKED ON BUTTON
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Now we focus more on FORM CONTROL of HTML
Member Form CODE
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Membership Form Example</title>
<script type="text/javascript">
function CalcAdd() {
//to set the DIV tag contents
document.getElementById("pMemberName").innerText= document.getElementById("txtMemberName").value;
document.getElementById("pMemberMobile").innerText = document.getElementById("txtMemberMobile").value;
document.getElementById("pMemberBirthDate").innerText = document.getElementById("txtMemberBirthDate").value;
document.getElementById("pMemberGender").innerText = document.getElementById("ddlGender").options[document.getElementById("ddlGender").selectedIndex].text;
document.getElementById("pMemberMarried").innerText = document.querySelector('input[name = marry]:checked').value;
}
</script>
<style>
#tbl{
border-collapse: collapse;
border: 1px solid black;
}
</style>
</head>
<body>
<h1 id="mainTitle">Member Detail</h1>
<br />
<table>
<tr>
<td>
Member Name
</td>
<td>
<input id="txtMemberName" type="text" />
</td>
</tr>
<tr>
<td>Mobile</td>
<td><input id="txtMemberMobile" type="text" /></td>
</tr>
<tr>
<td>Birth Date</td>
<td><input id="txtMemberBirthDate" type="text" /></td>
</tr>
<tr>
<td>Gender</td>
<td>
<select id="ddlGender">
<option>Male</option>
<option>Female</option>
</select>
</td>
</tr>
<tr>
<td>Married</td>
<td>
<input type="radio" name="marry" value="Yes Married">Yes<br>
<input type="radio" name="marry" value="Not Married" checked>No<br>
</td>
</tr>
<tr>
<td colspan="2" align="center">
<input type="button" name="clickbtn" value="Submit" onClick="CalcAdd()" style="font-size:19px;" />
</td>
</tr>
</table>
<br />
<br />
<table id="tbl" >
<tr>
<td>
<b> Member Name -----></b>
</td>
<td>
<p id="pMemberName"></p>
</td>
</tr>
<tr>
<td><b>Mobile -----></b></td>
<td><p id="pMemberMobile"></p></td>
</tr>
<tr>
<td><b>Birth Date -----></b></td>
<td><p id="pMemberBirthDate" > </p></td>
</tr>
<tr>
<td><b>Gender -----></b></td>
<td><p id="pMemberGender"></p></td>
</tr>
<tr>
<td><b>Married Status -----></b></td>
<td><p id="pMemberMarried"></p></td>
</tr>
</table>
</body>
</html>
OUT PUT ON LOAD:
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OUTPUT AFTER SUBMIT:
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Happy Coding…
I provide HTML, CSS and Dot Net (.NET), Asp.Net, PHP Training in Malad and western suburbs of Mumbai and on-line training.
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