getExpression Method

Retrieves the expression for the given property.

dhtml语法

vExpression = object.getExpression(sPropertyName)

Parameters

sPropertyName Required. Stringthat specifies the name of the property from which to retrieve the expression.

Return Value

Variant. Returns a variant value representing the expression of the property.

Remarks

The following syntax sections show how to retrieve an expression from supported Cascading Style Sheets (CSS) and DHTML Properties.
Use this syntax to retrieve an expression from a read/write property or from an expando property.
var sexpression = object.getexpression(spropertyname)
use this syntax to retrieve an expression from a css attribute.
var sexpression = object.style.getexpression(spropertyname)

Examples

The following examples demonstrate how to use the getExpression method to retrieve CSS properties.
This example uses the getExpression method to retrieve the width property of a span object.
<body>
<span id="trueBlueSpan"
style="background-color:lightblue; width:100px">
The width of this blue span is set inline at 100 pixels.
</span>
<span id="oldYellowSpan" style="background-color:lightyellow;
width:200px">
The width of this yelllow span is set inline at 200 pixels.
</span>
<br>
<span id="AlGreenSpan" style="background-color:lightgreen;
width:expression(trueBlueSpan.style.pixelWidth +
oldYellowSpan.style.pixelWidth)">
Click the button below to see the expression used to set
the width of this span.
</span>
<br>
<button onclick=alert(AlGreenSpan.style.getExpression("width"));>
See Expression</button>
</body>
In the following example, the setexpression method is used to set the width property of a blue input type=text object equal to the sum of the values in two other input type=text objects. when the user clicks the input type=button element, the getexpression method is used to display the expression.
<html>
<head>
<script language="JScript">
var s;
function fnInit() {
Box3.style.setExpression("width","eval(Box1.value) + eval(Box2.value)",
"jscript");
}
function getexp() {
s=Box3.style.getExpression("width");
alert("Expression for the width of the blue box is \n\n" + s +
"\n\nThe width property has a value of " + Box3.style.width);
}
</script>
</head>
<body onload=fnInit();>
<input type=text id="Box1" value=40>
<br><input type=text id="Box2" value=40>
<br><input type=text id="Box3" style="background-color:blue">
<br><input type=button id="Button2" value="Get expression" onclick="getexp()">
</body>
</html>
This feature requires Microsoft® Internet Explorer 5 or later. Click the following icon to install the latest version. Then reload this page to view the sample.

是否符合公共标准

There is no public standard that applies to this method.

Applies To

A, ACRONYM, ADDRESS, AREA, B, BDO, BIG, BLOCKQUOTE, BODY, BR, BUTTON, CAPTION, CENTER, CITE, CODE, COL, COLGROUP, currentStyle, CUSTOM, DD, DEL, DFN, DIR, DIV, DL, DT, EM, FIELDSET, FONT, FORM, hn, HR, I, IFRAME, IMG, INPUT type=button, INPUT type=checkbox, INPUT type=file, INPUT type=hidden, INPUT type=image, INPUT type=password, INPUT type=radio, INPUT type=reset, INPUT type=submit, INPUT type=text, INS, KBD, LABEL, LEGEND, LI, LISTING, MARQUEE, MENU, NOBR, OBJECT, OL, OPTION, P, PRE, Q, RT, RUBY, runtimeStyle, S, SAMP, SELECT, SMALL, SPAN, STRIKE, STRONG, style, SUB, SUP, TABLE, TBODY, TD, TEXTAREA, TFOOT, TH, THEAD, TR, TT, U, UL, VAR

更多语法参考

css attributes, about dynamic properties, recalc, removeexpression, setExpression