小编Dre*_*Cap的帖子

我试图理解这行代码.对r [e]做什么是减去和做什么？:

r = {}
for (e of s)
    r[e] = -~r[e] // What is this specific line assigning?

for (e in r)
    if (r[e] == 1)
        return e
return '_'

此代码解决的问题是这个(特定行被注释):

给定一个字符串s,找到并返回其中非重复字符的第一个实例.如果没有这样的字符,则返回'_'.

除了评论之外,我理解其他行.

我正在尝试使用MongoDB创建一个简单的React博客应用程序来存储帖子,但是当我尝试将Mongoose模型导入我的NewPost组件时,webpack将无法编译.

以下是错误:

WARNING in ./node_modules/mongoose/lib/drivers/index.js
10:13-49 Critical dependency: the request of a dependency is an expression

WARNING in ./node_modules/require_optional/index.js
82:18-42 Critical dependency: the request of a dependency is an expression

WARNING in ./node_modules/require_optional/index.js
90:20-44 Critical dependency: the request of a dependency is an expression

WARNING in ./node_modules/require_optional/index.js
97:35-67 Critical dependency: the request of a dependency is an expression

ERROR in ./node_modules/mongodb/lib/gridfs/grid_store.js
Module not found: Error: Can't resolve 'fs' in 'D:\mydocs\webdev\gitprojs\ReactBlogFinal\node_modules\mongodb\lib\gridfs'
 @ ./node_modules/mongodb/lib/gridfs/grid_store.js 42:7-20
 @ ./node_modules/mongodb/index.js
 @ ./node_modules/mongoose/lib/drivers/node-mongodb-native/binary.js
 @ ./node_modules/mongoose/lib/drivers/node-mongodb-native/index.js
 @ …

我是 Angular 2 的新手，我试图让它呈现一个包含其他模板/组件的视图组件。这就是我想要在 /home 路由上呈现的内容。问题：当我转到 /home 路线时，它转到一个空白页面而不是呈现我的模板。控制台中没有错误。

这是我的home.component.html：

<router-outlet></router-outlet>

<container>
  <header-component></header-component>
  <check-portfolio></check-portfolio>
  <portfolio-carousel></portfolio-carousel>
  <skill-section></skill-section>
  <need-help></need-help>
</container>

home.component.ts

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-home',
  templateUrl: './home.component.html',
  styleUrls: ['./home.component.scss']
})
export class HomeComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }

}

这是我的app.module.ts 的一些部分。我不确定我的app.component.html是否需要任何内容，但它是空白的：

const appRoutes: Routes = [
  { path: 'home', component: HomeComponent },
  {
    path: '',
    redirectTo: '/home',
    pathMatch: 'full'
  }
]

@NgModule({
  declarations: [
    AppComponent, …