跟踪已输出的JSON对象 [英] Track which JSON objects have been output
问题描述
我正在通过在加载页面时将索引设置为 randomNumber（）来随机输出20个左右的JSON对象。
我正在刷新每个已经在timeInterval上输出的JSON对象。
要跟踪已输出的JSON项目，我通过 arrUsed.push [index]
$ b
现在尝试编写将 update（）单独的每个JSON对象的函数，目前我仍然坚持如何更新每个div使用尚未输出的新JSON对象的信息（推送到 arrUsed [] ）。
这是我到目前为止的功能：
function reloadItems（）{
var itemTotal = $（'div。 。项'）长度; //最初加载的项目总数
var randomNumber = Math.floor（Math.random（）* 301）//返回数字
index = randomNumber; //将要在JSON数据中使用的索引设置为随机数
}
该数组包含已经输出的索引全局声明： arrUsed = []; 在将页面加载存储到数组中时最初输出的每个项目，以便覆盖该部分。这是一个选择随机JSON对象的问题，检查以确保它不在数组中/尚未输出，然后更新页面上的div。
这里是 （主程序）
首先，我们应该存储template.html在我们的全局模板变量中并触发 getJson（ ）功能：
template ='';
....
$（document）.ready（function（）{
$ .get（'template.html'，function（html）{template = html; getJson（）; }）;
}）;
然后，我们将JSON存储到我们的数据变量并触发 initialize（）函数：
数据=''; // JSON数据将存储在这里
myurl ='UK.top.20.html';
....
函数getJson（）{
$ .getJSON（myurl，function（JSON）{data = JSON; initialize（）;}）;
}
在这里，我们将调用 load（） 功能3次，立即用数据填充我们的3个产品div。然后我们将 i 设置回 2 （这样它将首先更改第3个DIV），并安排 tick（）在4.5秒内开火：
tick_time = 4500;
....
function initialize（）{//从前3
开始（i = 1; i< 4; i ++）{load（）; }
i = 2;
setTimeout（'tick（）'，tick_time）;
}
在我们解释 load（）之前 function，让我们来谈谈脚本底部的`String.prototype.f'：
String.prototype .f = function（）{var args = arguments; return this.replace（/ \ {（\d +）\} / g，function（m，n）{return args [n];}）; };
此函数类似于 String.Format（formatstring，arg1，arg2， arg3 ...）在C＃或 sprintf（$ formatstring，arg1，arg2，arg3 ...）在PHP中。这是一个例子：
formatstring ='玫瑰是{0}，紫罗兰是{1}，String.Format {2}和{3}！';
result = formatstring.f（'red'，'blue'，'rocks'，'you'）;
alert（result）;
正如你所看到的，这个 String.prototype.f 函数非常方便！
load（）函数要做的第一件事就是设置 rid = randomId（）; 。我们接下来看一下 randomId（）函数。它首先要做的是从1-20获取一个数字（基于我们的JSON数据的长度）。然后，它检查我们的看到的数组是否与我们的JSON数据大小相同，如果是 - 它将它设置回0.接下来它确保我们的最近没有看到 rid ，如果有，该函数会递归调用自身，直到获得唯一的随机ID。否则，我们在看到数组中存储 rid 并返回值。
function randomId（）{
rid = Math.floor（Math.random（）* data.results.length）;
if（seen.length == data.results.length）{seen.length = 0; }
if（$ .inArray（rid，seen）== -1）{
seen.push（rid）;
返回摆脱;
} else {return randomId（）; }
}
接下来我们的 load（）功能，我们设置 item 和 plat 作为方便的快捷方式。 plat_html 是Platform元素的临时存储位置。 for循环查看我们的JSON中的所有Platform数据，并使用我们的String.Format函数来填充我们的plat_html字符串。
最后，我们允许当前的i值（这是全局的）确定哪个 #product _ 得到更新， template.f 用JSON数据填充我们的模板，这是通过 .fadeIn（）完成平滑的jQuery动画。
function load（）{
rid = randomId（）;
item = data.results [rid];
plat = item.Platform;
plat_html ='';
for（var j = 0; j< plat.length; j ++）{
plat_html + = plat_fmt.f（
plat [j] .Hardware，
plat [j ]。市场
）;
}
$（'＃product_'+ i）.html（
template.f（
item.Image，
item.id，
item） .AgeRating，
item.WikiUrl，
item.Title，
item.Source，
item.Genre，
plat_html
）
） 。淡入（）;
}
最后，我们来看看递归 tick （）功能。它首先递增我们的全局 i 变量，并在它达到4时将其设置回1.然后我们执行动画 fadeOut（）在我们的 #product _ 元素上等到它完成，直到我们再次调用 load（）。然后，它安排自己再次在4.5秒内再次运行。
function tick（）{
i ++; if（i == 4）{i = 1; }
$（'＃product_'+ i）.fadeOut（function（）{load（）;}）;
setTimeout（'tick（）'，tick_time）;
}
就是这样！
I'm outputting 20 or so JSON objects randomly by setting the index to a randomNumber() initially when the page is loaded.
I'm refreshing each JSON object individually that has already been output on a timeInterval.
To keep track of which JSON items have been output I am storing the index of each item into an array via arrUsed.push[index]
Now trying to write the function that will update() each JSON objects individually and am currently stuck on how I can update the each div with the information from a new JSON object that has not already been output (pushed to the arrUsed[]).
Here's the function I have so far:
function reloadItems() {
var itemTotal = $('div.item').length; // Total number of items loaded initially
var randomNumber=Math.floor(Math.random()*301) //returns number
index = randomNumber; // Sets index to be used in JSON data to random number
}
The array that contains the already output index's is declared globally: arrUsed = []; Each item that is output initially when the page load is being stored to the array fine, so that part is covered. It's a matter of choosing a random JSON object, checking to ensure it is not in the array/not been output already, and then updating the div on the page.
Here's the previous question that has led me to this point
Here's a working example of a JSON/AJAX Ticker:
Per twhyler's specification, it randomly swaps an item every 4.5 seconds, keeping track of ones that have already been seen. Once they've all been seen, it starts over again:
Code Files:
- default.html (Main Program)
- template.html (Product Template)
- UK.top.20.html (JSON Data)
- ticker.js (jQuery)
- ticker.css (Style Sheet)
First, we should store template.html in our global template variable and fire the getJson() function:
template = '';
....
$(document).ready(function () {
$.get('template.html', function(html) { template = html; getJson(); });
});
Then, we'll store the JSON into our data variable and fire the initialize() function:
data = ''; // JSON data will be stored here
myurl = 'UK.top.20.html';
....
function getJson() {
$.getJSON(myurl, function (JSON) { data = JSON; initialize(); });
}
Here, we'll call the load() function 3 times to populate our 3 product div's with data right away. Then we set i back to 2 (that's so it will change the 3rd DIV first), and schedule tick() to fire in 4.5 seconds:
tick_time = 4500;
....
function initialize() { // Start with the first 3
for (i = 1; i < 4; i++) { load(); }
i = 2;
setTimeout('tick()', tick_time);
}
Before we explain the load() function, let's talk about `String.prototype.f' at the bottom of the script:
String.prototype.f = function () { var args = arguments; return this.replace(/\{(\d+)\}/g, function (m, n) { return args[n]; }); };
This function works similar to String.Format(formatstring, arg1, arg2, arg3...) in C# or sprintf($formatstring, arg1, arg2, arg3...) in PHP. Here's an example:
formatstring = 'Roses are {0}, Violets are {1}, String.Format {2} and so do {3}!';
result = formatstring.f('red', 'blue', 'rocks', 'you');
alert(result);
So as you can see, this String.prototype.f function comes in very handy!
The first thing the load() function will do is set rid = randomId();. Let's take a look at the randomId() function next. The first thing it does is get a number from 1-20 (based on the length of our JSON data). Then, it checks to see if our seen array is the same size as our JSON data, and if it is - it sets it back to 0. Next it makes sure that our rid hasn't been seen recently, and if it has, the function recursively calls itself again till it gets a unique random id. Otherwise, we store the rid in our seen array and return the value.
function randomId() {
rid = Math.floor(Math.random() * data.results.length);
if (seen.length == data.results.length) { seen.length = 0; }
if ($.inArray(rid, seen) == -1) {
seen.push(rid);
return rid;
} else { return randomId(); }
}
Next in our load() function after getting that random ID, we setup item and plat as convenient shortcuts. plat_html is a temporary storage place for the Platform elements. The for-loop looks at all the Platform data in our JSON and uses our String.Format function to fill our plat_html string.
Finally, we allow the current value of i (which is global) determine which #product_ gets updated, and template.f fills our template with JSON data which is done with a smooth jQuery animation thanks to .fadeIn().
function load() {
rid = randomId();
item = data.results[rid];
plat = item.Platform;
plat_html = '';
for (var j = 0; j < plat.length; j++) {
plat_html += plat_fmt.f(
plat[j].Hardware,
plat[j].Market
);
}
$('#product_' + i).html(
template.f(
item.Image,
item.id,
item.AgeRating,
item.WikiUrl,
item.Title,
item.Source,
item.Genre,
plat_html
)
).fadeIn();
}
Lastly, let's take a look at the recursive tick() function. It begins by incrementing our global i variable and setting it back to 1 when it reaches 4. Then we perform an animated fadeOut() on our #product_ element and wait till it's finished till we call load() again. Then, it schedules itself to run again in another 4.5 seconds.
function tick() {
i++; if (i == 4) { i = 1; }
$('#product_' + i).fadeOut(function() { load(); });
setTimeout('tick()', tick_time);
}
That's it!
这篇关于跟踪已输出的JSON对象的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
