mongoose

仅使用CSS就可以提高页面渲染速度的4个技巧

随声附和 提交于 2021-02-20 16:16:19
文末福利资源更新 本文将重点介绍4个可以用来提高页面渲染速度的CSS技巧。 1. Content-visibility 一般来说,大多数Web应用都有复杂的UI元素,它的扩展范围超出了用户在浏览器视图中看到的内容。在这种情况下,我们可以使用内容可见性( content-visibility )来跳过屏幕外内容的渲染。如果你有大量的离屏内容,这将大大减少页面渲染时间。 这个功能是最新增加的功能之一,也是对提高渲染性能影响最大的功能之一。虽然 content-visibility 接受几个值,但我们可以在元素上使用 content-visibility: auto; 来获得直接的性能提升。 让我们考虑一下下面的页面,其中包含许多不同信息的卡片。虽然大约有12张卡适合屏幕,但列表中大约有375张卡。正如你所看到的,浏览器用了1037ms来渲染这个页面 。 下一步,您可以向所有卡添加 content-visibility 。 在这个例子中,在页面中加入 content-visibility 后,渲染时间下降到150ms,这是6倍以上的性能提升。 正如你所看到的,内容可见性是相当强大的,对提高页面渲染时间非常有用。根据我们目前所讨论的东西,你一定是把它当成了页面渲染的银弹。 content-visibility 的限制 然而,有几个领域的内容可视性不佳。我想强调两点,供大家参考。

In mongoose, what is the difference between save(), insertOne() and updateOne(),when I want to add something new to a field that is already made?

半腔热情 提交于 2021-02-20 04:13:06
问题 for example I have a schema const listSchema=new mongoose.Schema({ name:String, items:Array }); const List=mongoose.model("List",listSchema); and I made a document const list=New List({ name: "list1", items:[item1, item2,item3] }); and then later I wanted to add a new item called item 4 so I used List.findOne({name:list1},function(err,foundList){ foundList.items.push(item4); foundList.save(); I know it might be a stupid question but it's confusing me. When I use .push I essentially added a

In mongoose, what is the difference between save(), insertOne() and updateOne(),when I want to add something new to a field that is already made?

主宰稳场 提交于 2021-02-20 04:12:26
问题 for example I have a schema const listSchema=new mongoose.Schema({ name:String, items:Array }); const List=mongoose.model("List",listSchema); and I made a document const list=New List({ name: "list1", items:[item1, item2,item3] }); and then later I wanted to add a new item called item 4 so I used List.findOne({name:list1},function(err,foundList){ foundList.items.push(item4); foundList.save(); I know it might be a stupid question but it's confusing me. When I use .push I essentially added a

In mongoose, what is the difference between save(), insertOne() and updateOne(),when I want to add something new to a field that is already made?

ぃ、小莉子 提交于 2021-02-20 04:11:00
问题 for example I have a schema const listSchema=new mongoose.Schema({ name:String, items:Array }); const List=mongoose.model("List",listSchema); and I made a document const list=New List({ name: "list1", items:[item1, item2,item3] }); and then later I wanted to add a new item called item 4 so I used List.findOne({name:list1},function(err,foundList){ foundList.items.push(item4); foundList.save(); I know it might be a stupid question but it's confusing me. When I use .push I essentially added a

How to perform $out in an aggregation in mongoose?

坚强是说给别人听的谎言 提交于 2021-02-19 08:53:12
问题 I looked for documentation of how to perform $out in an aggregation but I didn't find. This is my query: Top.aggregate([ {$sort: {created: -1}}, {$group: {_id:'$location', title:{$push: '$title'}}}, {$project: {location: '$location', mostRecentTitle: '$title'}}, {$out: "aggr_out"} ]).exec(function(err, docs) { console.log(docs); console.log(err) }); Schema: var schema = mongoose.Schema({ location: {type: String}, title: {type: String}, created: {type: Number, default: Math.floor(new Date() /

How can I find similar documents in MongoDB?

可紊 提交于 2021-02-19 06:19:07
问题 I have food db listing similar to: { Name: "burger", ingredients: [ {Item:"bread"}, {Item:"cheese"}, {Item:"tomato"} ] } How can I find documents that have the most similar items in ingredients ? 回答1: First of all, your data should be remodelled as below: { name: "Burger", ingredients: [ "bread", "cheese", "tomato", "beef" ] } The extra "Item" does not add any additional information nor does it help accessing the data in any way. Next, you need to create a text index. The docs state that text

Does MongoDB's $in clause has any max limit in number of arguments

雨燕双飞 提交于 2021-02-19 02:57:33
问题 When using MongoDB's $in clause with Aggregate , Does That has any max limit in number of arguments ? for example Model.aggregate( [ { $match : { '_Id' : { $in : ids } } } , { $group : { _id : '$roomId' , maxdate: { $max: "$date"}, } }, {$sort: { maxdate: -1} }, {$skip: skip}, {$limit: limitNum } ] In ids array , how many ids i can pass ? Currently i am not facing any issue with ids length till 50,000 ... but for safe side wanted to know the max limit. I have tried to search on Mongo doc ,

How to exclude null values from Mongoose populate query

[亡魂溺海] 提交于 2021-02-19 01:55:07
问题 I am building an app and I have create 2 models. const UserSchema = new Schema({ _id: Schema.Types.ObjectId, account:{ type: String, unique: true }, email: String, first_name: String, last_name: String } const VenueSchema = new Schema({ _id: Schema.Types.ObjectId, venue_type: String, capacity: Number }) and const MediatorSchema = new Schema({ _id: Schema.Types.ObjectId, account:{ type: String, unique: true }, user: {type: Schema.Types.ObjectId, ref:'User' } venue: {type: Schema.Types.ObjectId

How to exclude null values from Mongoose populate query

僤鯓⒐⒋嵵緔 提交于 2021-02-19 01:55:04
问题 I am building an app and I have create 2 models. const UserSchema = new Schema({ _id: Schema.Types.ObjectId, account:{ type: String, unique: true }, email: String, first_name: String, last_name: String } const VenueSchema = new Schema({ _id: Schema.Types.ObjectId, venue_type: String, capacity: Number }) and const MediatorSchema = new Schema({ _id: Schema.Types.ObjectId, account:{ type: String, unique: true }, user: {type: Schema.Types.ObjectId, ref:'User' } venue: {type: Schema.Types.ObjectId

Mongoosejs refresh a document

丶灬走出姿态 提交于 2021-02-19 01:21:17
问题 Suppose I have a document for example: var doc = Model.findOne({name:"name"}); Now if the document gets edited trough another connection the the database, doc doesn't hold the right information. I do need it, so I have to "refresh" or "redownload" it from the database. Is there any way to do this with only the object "doc"? 回答1: Assuming doc contains the document instance to refresh, you can do this to generically refresh it: doc.model(doc.constructor.modelName).findOne({_id: doc._id},