1、基礎(chǔ)準(zhǔn)備：
先來(lái)了解下，如何運(yùn)用js實(shí)現(xiàn)select動(dòng)態(tài)添加option。
//1.動(dòng)態(tài)創(chuàng)建selectfunction createSelect(){ var mySelect = document.createElement("select"); mySelect.id = "mySelect"; document.body.appendChild(mySelect);}//2.添加選項(xiàng)optionfunction addOption(){ //根據(jù)id查找對(duì)象， var obj=document.getElementById('mySelect'); //添加一個(gè)選項(xiàng) obj.add(new Option("文本","值")); //方法一： obj.options.add(new Option("text","value")); //方法二： for(var i=0;i<10;i++){ obj.options[i]=new Option("新文本","新值"); //方法三： }}//3.刪除所有選項(xiàng)optionfunction removeAll(){ var obj=document.getElementById('mySelect'); obj.options.length=0;}//4.刪除一個(gè)選項(xiàng)optionfunction removeOne(){ var obj=document.getElementById('mySelect'); var index=obj.selectedIndex; //index,要?jiǎng)h除選項(xiàng)的序號(hào) obj.options.remove(index);}//5.獲得選項(xiàng)option的值var obj=document.getElementById('mySelect');var index=obj.selectedIndex; //序號(hào)，取當(dāng)前選中選項(xiàng)的序號(hào)var val = obj.options[index].value;//6.獲得選項(xiàng)option的文本var obj=document.getElementById('mySelect');var index=obj.selectedIndex; var val = obj.options[index].text;//7.修改選項(xiàng)optionvar obj=document.getElementById('mySelect');var index=obj.selectedIndex; var val = obj.options[index]=new Option("新文本","新值");//8.刪除selectfunction removeSelect(){ var mySelect = document.getElementById("mySelect"); mySelect.parentNode.removeChild(mySelect);}2、時(shí)間聯(lián)動(dòng)實(shí)戰(zhàn)
時(shí)間聯(lián)動(dòng)的要點(diǎn)就是天數(shù)隨月份變化，考慮閏年，口訣：四年一閏，百年不閏，四百年再閏。
<!DOCTYPE html><html><head> <meta charset="utf-8" /> <title>日期和年份月份聯(lián)動(dòng)demo</title></head><body> <select id="year"> <option value="">請(qǐng)選擇年份</option> </select> <select id="month"> <option value="">請(qǐng)選擇月份</option> </select> <select id="day"> <option value="">請(qǐng)選擇日期</option> </select> <script> var year = document.getElementById("year"); var month = document.getElementById("month"); var day = document.getElementById("day"); var y = new Date().getFullYear(); //前后均有 for (i = (y - 30); i < (y + 30); i++) { year.options.add(new Option(i + "年", i)); //格式不要寫錯(cuò)，不要寫成add(new Option(i + "年"), i)。 } //只寫前或者后 // for(var i=y;i>1977;i--){ // year.options[y+1-i]=new Option(i+"年",i);//索引是options[],增加是new option(text,value) // } for (i = 1; i < 13; i++) { month.options.add(new Option(i + "月", i)); } var d = function () { day.length = 1; //初始化 if (year.value == " " || month.value == " ") { return; } else { var Days = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]; if ((year.value % 4 == 0 && year.value % 100 != 0) || year.value % 400 == 0) { Days[1]++; //判斷為閏年，二月天數(shù)加一 } for (i = 1; i <= Days[month.value - 1]; i++) { day.options.add(new Option((i + "日"), i)); } } } //刷新日期天數(shù) year.onchange = function () { d(); } month.onchange = function () { d(); } </script></body></html>
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