# 11 个对开发有帮助的 JS 技巧，进收藏夹当小词典吧！

English

### 1. 生成一个带有随机数的列表

``````Array.from({ length: 1000 }, Math.random)
// [ 0.6163093133259432, 0.8877401276499153, 0.4094354756035987, ...] - 1000 items``````

### 2.生成一个带有数字的列表

``````Array.from({ length: 1000 }, (v, i) => i)
// [0, 1, 2, 3, 4, 5, 6....999]``````

### 3. RGB→转换为十六进制

``````const rgb2hex = ([r, g, b]) =>
`#\${(1 << 24) + (r << 16) + (g << 8) + b}`.toString(16).substr(1);

rgb2hex([76, 11, 181]);
// #4c0bb5``````

### 4. 转换十六进制→RGB

``````const hex2rgb = hex =>
[1, 3, 5].map((h) => parseInt(hex.substring(h, h + 2), 16));

hex2rgb("#4c0bb5");
// [76, 11, 181]``````

### 5.奇数或偶数

``````const value = 232;

if (value & 1) console.log("odd");
else console.log("even");
// even``````

### 6.检查有效的 URL

``````const isValidURL = (url) => {
try {
new URL(url);
return true;
} catch (error) {
return false;
}
}

isValidURL('https://segmentfault.com/u/minnanitkong/articles')
// true

isValidURL("https//invalidto");
// false

``````

### 7.距离过去到现在时间表示

``````const fromAgo = (date) => {
const ms = Date.now() - date.getTime();
const seconds = Math.round(ms / 1000);
const minutes = Math.round(ms / 60000);
const hours = Math.round(ms / 3600000);
const days = Math.round(ms / 86400000);
const months = Math.round(ms / 2592000000);
const years = Math.round(ms / 31104000000);

switch (true) {
case seconds < 60:
return `\${seconds} second(s) ago"`;
case minutes < 60:
return `\${minutes} minute(s) ago"`;
case hours < 24:
return `\${hours} hour(s) ago"`;
case days < 30:
return `\${days} day(s) ago`;
case months < 12:
return `\${months} month(s) ago`;
default:
return `\${years} year(s) ago`;
}
};

const createdAt = new Date(2021, 0, 5);
fromAgo(createdAt); // 14 day(s) ago;``````

### 8. 用参数生成路径

``````const generatePath = (path, obj) =>
path.replace(/(:[a-z]+)/g, (v) => obj[v.substr(1)]);

const route = "/app/:page/:id";
generatePath(route, {
page: "products",
id: 85,
});
// /app/products/123``````

### 9.从路径获取参数

``````const getPathParams = (path, pathMap, serializer) => {
path = path.split("/");
pathMap = pathMap.split("/");
return pathMap.reduce((acc, crr, i) => {
if (crr[0] === ":") {
const param = crr.substr(1);
acc[param] = serializer && serializer[param]
? serializer[param](path[i])
: path[i];
}
return acc;
}, {});
};

getPathParams("/app/products/123", "/app/:page/:id");
// { page: 'products', id: '123' }

getPathParams("/items/2/id/8583212", "/items/:category/id/:id", {
category: v => ['Car', 'Mobile', 'Home'][v],
id: v => +v
});
// { category: 'Home', id: 8583212 }``````

### 10.用查询字符串生成路径

``````const getQueryParams = url =>
url.match(/([^?=&]+)(=([^&]*))/g).reduce((total, crr) => {
const [key, value] = crr.split("=");
total[key] = value;
}, {});

getQueryParams("/user?name=Orkhan&age=30");
// { name: 'Orkhan', age: '30' }``````

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