In: Root » » AJAX and JavaScript » The ''with'' Statement
learn more...Like the ternary conditional operator, the with statement is a shortcut. Instead of having to list all of the properties of an object by repeating the basic object, you can state the bulk of the object in a with statement and then the properties within the context of the with statement. For example, take a typical form object. First you must state the object as follows: document.formName...
Then you follow with the element names and values: …elementName.value
Thus, your statement would be document.formName,elementName.value
A typical form could include several different elements, such a first name, last name, address, city, state, ZIP code, Social Security number, and all other kinds of property details. Using the with statement, you can specify the object name once and then follow it with all of the properties and their values in this format: with (object) {
statements with properties only
}
The statements are typically property values. In the following simple example, the script uses a single with statement and then places the property values of the object in the statements within the with context: <html>
<head>
<title>with</title>
<script language="JavaScript">
function showEm(){
with (document.customer) {
var alpha=fname.value;
var beta=lname.value;
var gamma=address.value;
var delta=city.value;
var epsilon=state.value;
}
var fullName=alpha + " " + beta + "\n";
var livesHere=gamma + "\n" + delta + ", " + epsilon;
alert(fullName + livesHere);
}
</script>
</head>
<body bgColor="cornsilk">
<form name="customer">
<input type=text name="fname"> First Name:
<input type=text name="lname"> Last Name:
<br>
<input type=text name="address"> Address:
<br>
<input type=text name="city"> City:
<input type=text name="state" size=2> State:
<p>
<input type=button value="Click Here" onClick="showEm()">
</body>
</html>
When and where to best use the with statement depends on the application, but, as can be seen from the example, it helps to clean up and simplify references to multiple properties in an object.
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