<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>無標題文檔</title><script>function getCity(){?? ??? ?var privince=document.getElementById("province");?? ? var city=document.getElementById('city');?? ?var shu=privince.selectedIndex;alert(shu);/*if 語句 - 只有當指定條件為 true 時，使用該語句來執行代碼if...else 語句 - 當條件為 true 時執行代碼，當條件為 false 時執行其他代碼*/switch(shu){?? ?case 1:???? city.options.length=0;?? ? city.add(new Option("朝陽","朝陽"));?? ?? city.add(new Option("朝陽","朝陽"));?? ??? city.add(new Option("朝陽","朝陽"));?? ? break;?? ? ?? ??? ??? ??? ?case 2:?? ??? ??? ?city.options.length=0;?? ??? ? city.add(new Option("東莞","東莞"));?? ??? ? city.add(new Option("東莞","東莞"));?? ??? ? city.add(new Option("東莞","東莞"));?? ??? ? break?? ??? ? ?? ??? ?? ?default:?? ?city.options.length=0;?? ??? ? city.add(new Option("遼寧","遼寧"));?? ??? ?? city.add(new Option("遼寧","遼寧"));?? ??? ??? city.add(new Option("遼寧","遼寧"));?? ??? ? ?? ??? ?? ??? ??? ??? ?}}</script></head><body>?? <FORM METHOD=POST ACTION="" name="form1"> ?<select name="province" id="province" onchange="getCity()" >?<option? selected="selected">請選擇所在省份</option> ??<option >北京</option><option? value="廣州">廣州</option><option? value="山東">山東</option></select><select id="city" name="city" ></select></FORM></body></html>
就今天在做一個js的二級級聯是我發現使用if,if elseif,和switch進行條件選擇時市的結果不一樣？
向日葵一族
2016-12-23 18:31:25