我有下面的代码,有2个独立的问题,所以请耐心等待:
问题1 [获取?]:JSON更改时,显示的数据不会更改。听起来像是缓存问题,因为我无法在原始请求旁边看到任何HTTP请求。如何强制每次再次下载JSON文件?
问题2 [把手?]:带有$(document.body).append(html);在循环中,它不断重写而不是编辑值。我该如何更改?
这里是代码:
javascript.js:
async function fetch_json() {
try {
var resp = await fetch('http://localhost:8000/data.json', {mode: 'cors'});
var jsonObj = await jsonify(resp);
return jsonObj;
} catch (error) {
// all errors will be captured here for anything in the try block
console.log('Request failed', error);
}
}
html页面:
<script id="handlebars-demo" type="text/x-handlebars-template">
<div>
{{#each this}}
Name : {{name}} Value : {{value}} <br>
{{/each}}
</div>
</script>
<script type="text/javascript">
var test_data = [{ "name" : "john doe", "value" : "developer" },{ "name" : "bob boby", "value" : "developer2" }];
setInterval(function() {
test_data = fetch_json()
.then(function(result) {
html = templateScript(result);
//$(document.body).append(html);
})
}, 1000);
var template = document.getElementById('handlebars-demo').innerHTML;
Compile the template data into a function
var templateScript = Handlebars.compile(template);
var html = templateScript(test_data);
$(document.body).append(html);
</script>
任何帮助将是最大的感谢,谢谢!
您应该创建一个DOM元素来保存所生成的HTML。我在示例中创建了<div id="content"></div>
。您可以每次使用$()。html()覆盖HTML而不是附加。$('#content')
选择id = content的DOM元素,然后用字符串覆盖.html(string)
内部的HTML。
缓存清除的一种常见方法是将时间戳记作为url查询参数附加到url,我已通过串联nocache='+new Date().getTime()
来完成。在生产中的正常使用中,构建后通常会为每个资源的每个版本生成唯一的标识符。
// for demo purposes, overwrite value property with username property
jsonify = x => x.json().then(x => x.map(x => ({ ...x,
value: x.username
})));
async function fetch_json() {
try {
// append timestamp to prevent caching
var resp = await fetch('https://jsonplaceholder.typicode.com/users?nocache=' + new Date().getTime(), {
mode: 'cors'
});
var jsonObj = await jsonify(resp);
return jsonObj;
} catch (error) {
// all errors will be captured here for anything in the try block
console.log('Request failed', error);
}
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/handlebars.js/4.7.6/handlebars.js" integrity="sha256-ZafrO8ZXERYO794Tx1hPaAcdcXNZUNmXufXOSe0Hxj8=" crossorigin="anonymous"></script>
<div id="content"></div>
<script id="handlebars-demo" type="text/x-handlebars-template">
<div>
{{#each this}} Name : {{name}} Value : {{value}} <br> {{/each}}
</div>
</script>
<script type="text/javascript">
var test_data = [{
"name": "john doe",
"value": "developer"
}, {
"name": "bob boby",
"value": "developer2"
}];
setInterval(function() {
test_data = fetch_json()
.then(function(result) {
html = templateScript(result);
$('#content').html(html);
})
}, 2000);
var template = document.getElementById('handlebars-demo').innerHTML;
//Compile the template data into a function
var templateScript = Handlebars.compile(template);
var html = templateScript(test_data);
$('#content').html(html);
</script>