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Retrieving/changing a text box value

allowed in the text box. So to create a text box that can display 25 characters at a time but has a maxi-

mum length of 50, the following code can be used:

The

element always renders a multiline text box. To specify how large the text box should

be, you can use the

rows

attribute, which specifies the height of the text box in number of characters,

and the

cols

attribute, which specifies the width in number of characters (similar to

size

for an

element). Unlike

, the initial value of a

must be enclosed between

and

</textarea>

, as shown here:

<textarea rows=”25” cols=”5”>initial value</textarea>

Also unlike the

element, a

cannot specify the maximum number of characters

allowed.

Retrieving/changing a text box value

Even though they are different elements, both

and

support the

same property,

value

, to retrieve the text contained in the text box. Consider the following example:

<html>

<head>

<title>Retrieving a Textbox Value Example</title>

function getValues() {

var oTextbox1 = document.getElementById(“txt1”);

var oTextbox2 = document.getElementById(“txt2”);

alert(“The value of txt1 is \”” + oTextbox1.value + “\”\n” +

“The value of txt2 is \”” + oTextbox2.value + “\””);

}

</script>

</head>

<body>

</body>

</html>

This example displays two text boxes, a single-line and a multiline, as well as a button. When you click

the button, an alert is displayed showing the values contained in each text box. Try typing into each text

box a couple of times and then click the button.

Because the value property is a string, you can use all the properties and methods of a string. For exam-

ple, you can get the length of text inside a text box by using the

length

property:

<html>

<head>

<title>Retrieving a Textbox Length Example</title>

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Forms and Data Integrity

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