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133 lines
3.9 KiB
Markdown
133 lines
3.9 KiB
Markdown
省市联动案例：
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```html
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="UTF-8">
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<meta http-equiv="X-UA-Compatible" content="ie=edge">
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<title>Document</title>
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</head>
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<body>
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<select name="" id="province">
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<option value="">请选择省份</option>
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</select>
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<select name="" id="city">
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<option value="">请选择市</option>
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</select>
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<select name="" id="area">
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<option value="">请选择区</option>
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</select>
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</body>
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<script>
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var province = document.querySelector("#province");
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var city = document.querySelector("#city");
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var area = document.querySelector("#area");
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var xhr = new XMLHttpRequest();
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xhr.open("get", "http://api.yytianqi.com/citylist/id/2", true);
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xhr.send();
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xhr.onreadystatechange = function () {
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if (this.readyState == 4 && this.status == 200) {
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var json = JSON.parse(this.responseText);
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var jsonList = json.list;
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var provinceHtml = "<option value=''>请选择省份</option>";
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jsonList.map(function (item) {
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var provinceId = item["city_id"];
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var provinceName = item["name"];
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provinceHtml += `<option value="${provinceId}">${provinceName}</option>`;
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});
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province.innerHTML = provinceHtml;
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// 当province的 select 里面value的值改变的时候
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var cityList = [];
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province.onchange = function () {
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var provinceId = this.value; // 省的id
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var province = jsonList.filter(function (item) {
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return item["city_id"] == provinceId;
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})[0];
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cityList = province.list;
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var cityHtml = '<option value="">请选择市</option>';
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cityList.map(function (item) {
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var cityId = item["city_id"];
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var cityName = item["name"];
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cityHtml += `<option value=${cityId}>${cityName}</option>`
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});
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city.innerHTML = cityHtml;
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};
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// 当city的select 里面value的值改变的时候
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city.onchange = function () {
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var cityId = this.value;
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var city = cityList.filter(function (item) {
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return item["city_id"] == cityId;
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})[0];
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var areaList = city.list;
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// 判断是否为直辖市
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if (areaList) {
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area.style.display = "inline-block";
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var areaHtml = '<option value="">请选择区</option>';
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areaList.map(function (item) {
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var areaId = item["city_id"];
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var areaName = item["name"];
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areaHtml += `<option value="${areaId}">${areaName}</option>`;
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});
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area.innerHTML = areaHtml;
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} else {
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area.style.display = "none";
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}
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};
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}
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};
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</script>
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</html>
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```
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注意事项：
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> Ajax最好不要用全局变量，因为Ajax请求需要时间，你获取到的可能是未更新的值。
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>
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> 如果非要使用的话，使用回调函数来执行这个变量。
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```js
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var global = "";
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var xhr = new XMLHttpRequest();
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xhr.open("get", "./data", true);
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xhr.send();
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xhr.onreadystatechange = function () {
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if (this.readyState == 4 && this.status == 200) {
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global = this.responseText;
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show(global);
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}
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};
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function show(data) {
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alert(data);
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}
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```
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上面省市联动中，在获取地区的列表时，需要用到市的信息，所以我们将市的列表提升出来:
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`var cityList = [];`
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由于这里 cityList 并不是在Ajax中获取的数据，所以没有这个考虑。但是上面的坑是一定要注意的。 |