3.22. if
| Element type | if |
| Attributes | cond |
| Parents | block | catch | error | filled | help | if | noinput | nomatch |
| Children | assign | audio | clear | disconnect | else | elseif | enumerate | exit | goto | if | log | prompt | reprompt | return | script | submit | throw | value | var |
| Description | An executable element implementing the if-then-else conditional logic. |
DTD
<!ENTITY % if.attrs "cond %expression; #REQUIRED" > <!ELEMENT if (%executable.content; | elseif | else)* > <!ATTLIST if %if.attrs; >
Language model
Attributes
cond : expression
An ECMAScript expression that evaluates to a boolean. If it evaluates to true, the contents within the if element will be executed until an elseif or else element is encountered or the closing </if> tag is encountered.
Children
elseif elements
Marks the beginning of an else-if code block within this if element.
else element
Marks the beginning of the else code block within this if element.
executable.content
Elements and audible nodes that may be executed depending on the evaluation of this if element's cond attribute, the cond attributes of sibling elseif elements, and their position relative to sibling elseif and else elements.
Examples
Example 3-25. A form demonstrating if-else logic
<?xml version="1.0" encoding="iso-8859-1"?>
<vxml version="1.0">
<form id="pick">
<field name="select">
<grammar>one|two|three</grammar>
<prompt>Pick a number from one to three.</prompt>
<filled>
<if cond="select=='one'">
<prompt>Your selection was one.</prompt>
<else/>
<prompt>Your selection was greater than one.</prompt>
</if>
</filled>
</field>
</form>
</vxml>
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