我可以在JavaScript中限制数组的长度吗? [英] Can I limit the length of an array in JavaScript?
问题描述
我想显示产品浏览历史记录,因此我将产品ID存储在浏览器Cookie中。
I want to display the product browsing history, so I am storing the product ids in a browser cookie.
由于历史记录列表仅限于5个项目,我将cookie值转换为数组,然后检查它的长度,并切割冗余。
Because the list of history is limited to 5 items, I convert the cookie value to an array, then check the length of it and cut the redundant.
下面的代码是我试过的,但它不工作;
The code below is what I have tried, but it does not work; the array item isn't removed.
我想问如何限制数组长度,以便它只能存储5个项目?
I would like to ask how to limit the array length so it can only store 5 items?
或
如何在数组索引4之后剪切项目?
How can I cut the items after the array index 4?
var id = product_id;
var browseHistory = $.cookie('history');
if (browseHistory != null) {
var old_cookie = $.cookie('history');
var new_cookie = '';
if (old_cookie.indexOf(',') != -1) {
var arr = old_cookie.split(',');
if (arr.length >= 5) {
arr.splice(4, 1)
}
}
new_cookie = id + ',' + old_cookie;
$.cookie('history', new_cookie, { expires: 7, path: '/' });
} else {
$.cookie('history', id, { expires: 7, path: '/' });
}
推荐答案
正确:
arr.splice(4, 1)
这会从索引4移除1个项目。请参阅此处
this will remove 1 item at index 4. see here
我想要使用切片:
arr.slice(0,5)
这假设您的所有代码(Cookie等)都能正常工作
This assumes all the rest of your code (cookies etc) works correctly
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