javascript里类似select case该如何用
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作者:佚名
来源:InterNet 加入时间:2005-4-1 |
switch Statement<br> Enables the execution of one or more statements when a specified expression's value matches a label.<br> <br> switch (expression) {<br> case label :<br> statementlist<br> case label :<br> statementlist<br> ...<br> default :<br> statementlist<br> } <br> <br> Arguments<br> expression<br> <br> The expression to be evaluated.<br> <br> label<br> <br> An identifier to be matched against expression. If label === expression, execution starts with the statementlist immediately after the colon, and continues until it encounters either a break statement, which is optional, or the end of the switch statement.<br> <br> statementlist<br> <br> One or more statements to be executed.<br> <br> Remarks<br> Use the default clause to provide a statement to be executed if none of the label values matches expression. It can appear anywhere within the switch code block. <br> <br> Zero or more label blocks may be specified. If no label matches the value of expression, and a default case is not supplied, no statements are executed.<br> <br> Execution flows through a switch statement as follows: <br> <br> Evaluate expression and look at label in order until a match is found. <br> If a label value equals expression, execute its accompanying statementlist. <br> Continue execution until a break statement is encountered, or the switch statement ends. This means that multiple label blocks are executed if a break statement is not used. <br> If no label equals expression, go to the default case. If there is no default case, go to last step. <br> Continue execution at the statement following the end of the switch code block. <br> Example<br> The following example tests an object for its type. <br> <br> function MyObject() {<br> ...}<br> <br> switch (object.constructor){<br> case Date:<br> ...<br> case Number:<br> ...<br> case String:<br> ...<br> case MyObject:<br> ...<br> default: <br> ...<br> }<br> Requirements<br> Version 3<br> <br>
[文章录入员:nancy] |
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