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阅读内容 录音

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say -f 1.txt -o 1.aiff

转 mp3

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lame -m m 1.aiff 1.mp3

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clientX vs pageX

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let i = 0;

while (i < scores.length) {
    console.log(scores[i]);
    i++;
}
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let i = 0;

do {
    console.log(scores[i]);
    i++;
} while (i < scores.length);
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for (let i = 0; i < scores.length; i++) {
    console.log(scores[i]);
}
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for (i in scores) {
    console.log(scores[i]);
}
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for (score of scores) {
    console.log(score);
}

forEach

map

reduce

reduceRight

flatMap

filter

every

some

indexOf

lastIndexOf

find

findIndex

keys

entries

includes

Spread …

via https://www.w3schools.com/js/js_array_iteration.asp

via https://www.w3schools.com/jsref/jsref_obj_array.asp

at 

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const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits.at(-2);

array.slice(start, end)

The slice() method does not change the original array.

array.splice(index, howmany, item1, ….., itemX)

The splice() method overwrites the original array.

copyWithin

array.copyWithin(target, start, end)

Posted on

Tools -> Developer -> New Snippet…

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<snippet>
    <content><![CDATA[console.log($1);$0]]></content>
    <tabTrigger>log</tabTrigger>
    <scope>text.plain,source.js,source.ts</scope>
    <description>console.log()</description>
</snippet>

保存为 log.sublime-snippet

使用：

log+回车

Posted on Edited on

npm –save 和–save-dev的区别

使用–save 安装的包是项目发布之后还需要依赖的包， 如axiox , express等包，等项目上线以后还需使用。

使用–save-dev 安装的包则是开发时依赖的包，等项目上线则不会使。

npm install 和 npm i 是一样

–save 和 -S 是一样
–save-dev 和 -D 是一样的

tsc

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npm i tsc -D
npx tsc --init

npx tsc -w

任何 1.ts 生成 1.js

也可以修改 tsconfig.json 配置

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// "outFile":"./",
// "outDir": "./",

类型

  • boolean

  • number

  • string

  • Explicit

  • Implicit

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let firstName: string = "Dylan";

unknown 比 any 安全

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let w: unknown = 1;

let v: any = true;

date 性能

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Date.now()  // 最快
new Date().getTime();
+new Date // 最慢

via https://www.measurethat.net/Benchmarks/Show/9412/0/new-date-vs-new-dategettime-vs-datenow-100k

interface 和 type 区别

  • 接口是通过继承的方式来扩展，类型别名是通过 & 来扩展。
  • 接口可以自动合并，而类型别名不行

https://zhuanlan.zhihu.com/p/351213183

到底应该用 type 还是 interface ？
Because an interface more closely maps how JavaScript objects work by being open to extension, we recommend using an interface over a type alias when possible.
On the other hand, if you can’t express some shape with an interface and you need to use a union or tuple type, type aliases are usually the way to go.

意思是说能用 interface 的地方就用 interface，否则用 type，其实这个解释官方说的也比较明确，这样使用的原因是因为更贴合 JavaScript 对象的工作方式，再清晰一些，如果我们是定义一个 object，那么最好是使用 interface 去做类型声明，什么时候用 type 呢，当定义一个 function 的时候，用 type 会更好一些

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// the `?` operator here marks parameter `c` as optional
function add(a: number, b: number, c?: number) {
  return a + b + (c || 0);
}

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class Person {
  private name: string;

  public constructor(a: string) {
    this.name = a;
  }

  public getName(): string {
    return this.name;
  }
}
      
const person = new Person('david');

console.log(person)

//console.log(person.name)

console.log(person.getName())

class Property ‘’ has no initializer and is not definitely assigned in the constructor

  1. tsconfig.json 关掉严格
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"compilerOptions": {
  "strictPropertyInitialization":false
}
  1. undefined
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employees : Employee[] | undefined;
  1. definite assignment assertion
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employees!: Employee[];
  1. init
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employees: Employee[] = [];
  1. Assignment in the Constructor

employees: Employee[];

constructor() {
this.employees=[];
}

super

父级构造函数

?? 对比 ||

使用 ?? 时，只有当值1为null或undefined时才返回值2；

使用 || 时，值1会转换为布尔值判断，为true返回值1，false 返回值2

Posted on

0: Main button pressed, usually the left button or the un-initialized state

1: Auxiliary button pressed, usually the wheel button or the middle button (if present)

2: Secondary button pressed, usually the right button

3: Fourth button, typically the Browser Back button

4: Fifth button, typically the Browser Forward button

Posted on

下载的美剧是1目录1集，想考出来

即

a1/a1.mp4
a2/a2.mp4

->

a1.mp4
a2.mp4

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find . -type f -exec mv {} ./ \;

报错！重名！

a1.mp4/a1.mp4
a2.mp4/a2.mp4

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find . -type f -exec mv {} ../ \;

那就往上一层（然后删除空目录，再考回去）

Posted on Edited on

hi

Posted on

数据来源：

https://data.cdc.gov/NCHS/Provisional-COVID-19-Deaths-by-Sex-and-Age/9bhg-hcku

temp1 是第一个 td（Age Group）

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var td = $(temp1);
var table = td.closest('table')
var n = td.index()
var rs = []

table.find('tr').each((a,b)=>{
	console.log(b)
	let td1 = $(b).find('td:eq('+n+')');
	let td2 = $(b).find('td:eq('+(n+1)+')');
	//console.log(td1,td2)
	let t1 = $.trim($(td1).text())
	let t2 = $.trim($(td2).text())
	console.log(t1,t2)
	rs.push({
		t:t1,
		v:t2
		})
})

美国 covid 死亡人数

美国人口 3.319 亿 (2021 年)

从 2020-01-01 到 2022-11-26

  • 各种原因死亡人数： 9,691,052
  • 新冠：1,073,957
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[
  {
      "t": "All Ages 各年龄段总数",
      "v": "1,073,957"
  },
  {
      "t": "Under 1 year",
      "v": "385"
  },
  {
      "t": "0-17 years",
      "v": "1,372"
  },
  {
      "t": "1-4 years",
      "v": "208"
  },
  {
      "t": "5-14 years",
      "v": "428"
  },
  {
      "t": "15-24 years",
      "v": "2,858"
  },
  {
      "t": "18-29 years",
      "v": "6,688"
  },
  {
      "t": "25-34 years",
      "v": "11,870"
  },
  {
      "t": "30-39 years",
      "v": "19,136"
  },
  {
      "t": "35-44 years",
      "v": "29,076"
  },
  {
      "t": "40-49 years",
      "v": "44,856"
  },
  {
      "t": "45-54 years",
      "v": "69,339"
  },
  {
      "t": "50-64 years",
      "v": "196,036"
  },
  {
      "t": "55-64 years",
      "v": "153,924"
  },
  {
      "t": "65-74 years",
      "v": "243,622"
  },
  {
      "t": "75-84 years",
      "v": "278,544"
  },
  {
      "t": "85 years and over",
      "v": "283,703"
  }
]
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let total = rs.reduce((pre,a)=>{    
  return  a.v.replace(/,/g,'')*1 + pre
},0)

rs.forEach((a)=>{    
	a.percent = (a.v.replace(/,/g,'')*100/ total).toFixed(3) + '%'
})

对比参考

  • 中国人口：14.12 亿 (2021 年)
  • 2021年 死亡 1014万人 死亡率为7.18‰