As a user of the web, you know that web pages both display and accept data. In this chapter we are going to learn more about how web pages handle data input using HTML forms. An HTML form is used to accept input from the user and send that data to the server.
To declare a form in HTML use the
<form> tag with open and closing tags. This form element
will serve as container for various types of other elements that are designed to capture
input from the user.
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<html> <head> <title>Form Example</title> </head> <body> <!-- empty form --> <form></form> </body> </html>
<form></form> will not appear on a web page until inputs have been
added inside of it. Below we have added one basic
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<html> <head> <title>Form Example</title> </head> <body> <form> <input type="text"/> </form> </body> </html>
input element is used to add interactive fields, which allow the user to enter data.
input elements have two very important attributes: name and type.
nameattribute is used to identify the input's value when the data is submitted
typeattribute defines which type of value of the input represents
<input type="text" name="username"/>
<input type="text"/> tags are self closing. Self-closing tags are single tags
/> at the end.
Values are NOT submitted for an
<input> unless it has a
Forms normally contain more than one input.
<label> tags are used to provide a textual
label, which informs the user of the purpose of the field. The simplest usage of
<label> tags is to wrap them around
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<html> <head> <title>Form Example</title> </head> <body> <form> <label>Username <input type="text" name="username"/></label> <label>Team Name <input type="text" name="team"/></label> </form> </body> </html>
A second way to relate a
<label> tag to an
<input> is to use the
id attribute of
input and the
for attribute of
label. The two are related by setting
equal to the
<input id="username">, these two attributes must be EQUAL.
for is used, the
<input> does NOT have to be inside of the
<label for="username">Username</label> <input id="username" name="username" type="text"/>
What happens when a
<label> is clicked? The answer depends on what the
For text inputs, when the label is clicked, then the input gains focus. An element with focus is currently selected by the browser and ready to receive input.
Try clicking on the
Team Name labels below. What
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<form> <label>Username <input type="text" name="username"/></label> <label>Team Name <input type="text" name="team"/></label> </form>
For non-text inputs, when the label is clicked, a value is selected. This behavior
can be seen with
checkbox elements which we will learn more about soon.
Click on the label text to the associated checkbox input element gain focus.
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<form> <label>Subscribe to Newsletter <input type="checkbox" name="newsletter"/> </label> </form>
value attribute of an
<input> tag can be used to set the default value. If the
value attribute is declared, then the browser will show that value in the input. The user
can choose to update the value by typing in the input box.
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What is the purpose of the
name attribute for
input attribute sets the default value?