Interesting JavaScript questions: Front-end paging
Paging on the front end is a very cool thing. It can relieve the pressure on the server side, reduce the number of requests and the amount of server calculations.
However, you need to make it into a component so that it can be easily called everywhere. Otherwise, it would be thankless to write one for every page.
It is best to implement such a helper class, as shown below:
//第一个参数是要分页的JSON对象 //第二个参数是每一页的最大项数 var helper = new PaginationHelper(['a','b','c','d','e','f'], 4); //总共多少页 => Math.ceil(6 / 4) helper.pageCount(); // 2 //总共多少项 => array.length helper.itemCount(); // 6 //求当前页的项数,这个页的索引是从0开始的 helper.pageItemCount(0); // 4 //6 - 4 = 2 helper.pageItemCount(1); // 2 //总共才2页,所以当前页无效,返回-1 helper.pageItemCount(2); // -1 //当前索引是属于第几页? helper.pageIndex(5); // 1 helper.pageIndex(2); // 0 //总共都才6条记录,所以20无效 helper.pageIndex(20); // -1 //索引小于0,无效返回-1 helper.pageIndex(-10); // -1
Whether it is front-end paging or back-end paging, the idea is the same, both are relatively simple, but you must pay attention to illegal value processing.
function PaginationHelper(collection, itemsPerPage){ this.collection = collection; this.itemsPerPage = itemsPerPage; } PaginationHelper.prototype.itemCount = function() { return this.collection.length; } PaginationHelper.prototype.pageCount = function() { return Math.ceil(this.itemCount() / this.itemsPerPage); } PaginationHelper.prototype.pageItemCount = function(pageIndex) { if(pageIndex < this.pageCount() - 1){ return this.itemsPerPage; } else if(pageIndex == this.pageCount() - 1){ return this.itemCount() - pageIndex * this.itemsPerPage; } else{ return -1; } } PaginationHelper.prototype.pageIndex = function(itemIndex) { if(itemIndex >=0 && itemIndex < this.itemCount()){ return Math.floor(itemIndex / this.itemsPerPage); } return -1; }
The above is the interesting JavaScript question: the content of front-end paging. For more related content, please pay attention to the PHP Chinese website (www.php.cn)!

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