码云前端开发 2021-11-03

这14个JavaScript函数提升你的工作效率

文章目录隐藏

randomNumber()
capitalize()
toTop()
truncate()
appendURLParams() & getURLParams()
softDeepClone()
scrollToHide()
getInnerHTML()
humanFileSize ()
setLocalItem() & getLocalItem()
getTimes()
formatNumber()
getScreenWidth()
toFormData()
结语

在本文中，分享一些我几乎在每个项目中都会用到的一些函数。

randomNumber()

获取指定区间的随机数。

**
 * 在最小值和最大值之间生成随机整数。
 * @param {number} min Min number
 * @param {number} max Max Number
 */
export const randomNumber = (min = 0, max = 1000) =>
  Math.ceil(min + Math.random() * (max - min));

// Example
console.log(randomNumber()); // 97

capitalize()

将字符串的第一个字母变为大写。

/**
 * Capitalize Strings.
 * @param {string} s String that will be Capitalized
 */
export const capitalize = (s) => {
  if (typeof s !== "string") return "";
  return s.charAt(0).toUpperCase() + s.slice(1);
}

// Example
console.log(capitalize("cat")); // Cat

toTop()

滚到到底部，可以通过 behavior 属性指定滚动速度状态。

/**
 * Scroll to top
 */
export const toTop = () => {
  window.scroll({ top: 0, left: 0, behavior: "smooth" });
};

truncate()

这对于长字符串很有用，特别是在表内部。

/**
 * 截断字符串....
 * @param {string} 要截断的文本字符串
 * @param {number} 截断的长度
 */
export const truncate = (text, num = 10) => {
  if (text.length > num) {
    return `${text.substring(0, num - 3)}...`
  }
  return text;
}

// Example
console.log(truncate("this is some long string to be truncated"));  

// this is...

appendURLParams() & getURLParams()

快速添加和获取查询字符串的方法，我通常使用它们将分页元数据存储到url。

/**
 * Appen query string and return the value in a query string format.
 * @param {string} key
 * @param {string} value
 */
export const appendURLParams = (key, value) => {
  const searchParams = new URLSearchParams(window.location.search).set(key, value);
  return searchParams.toString();
};

// example
console.log(appendURLParams("name", "youssef")) // name=youssef

/**
 * Get param name from URL.
 * @param {string} name
 */
export const getURLParams = (name) => new URLSearchParams(window.location.search).get(name);

// Example
console.log(getURLParams(id)) // 5

softDeepClone()

这个方法是经常被用到的，因为有了它，我们可以深度克隆嵌套数组或对象。

不过，这个函数不能与new Date()、NaN、undefined、function、Number、Infinity等数据类型一起工作。

你想深度克隆上述数据类型，可以使用 lodash 中的 cloneDeep() 函数。

/**
 * Deep cloning inputs
 * @param {any} input Input
 */
export const softDeepClone= (input) => JSON.parse(JSON.stringify(input));

scrollToHide()

上滚动以显示 HTML 元素，向下滚动以将其隐藏。

/**
 * 下滚动时隐藏 HTML 元素。
 * @param {string} 元素的 id
 * @param {string} distance in px ex: "100px"
 */
export const scrollToHide = (id, distance) => {
  let prevScrollpos = window.pageYOffset;
  window.onscroll = () => {
    const currentScrollPos = window.pageYOffset;
    if (prevScrollpos > currentScrollPos) {
      document.getElementById(id).style.transform = `translateY(${distance})`;
    } else {
      document.getElementById(id).style.transform = `translateY(-${distance})`;
    }
    prevScrollpos = currentScrollPos;
  };
};

getInnerHTML()

每当服务器返回一串 HTML 元素时，我都会使用它。

/**
 * 获取 HTML 字符串的内部 Text
 * @param {string} str A string of HTML
 */
export const getInnerHTML = (str) => str.replace(/(<([^>]+)>)/gi, "");

humanFileSize ()

传入字节为单位的文件，返回我们日常所熟悉的单位。

/**
 * Converting Bytes to Readable Human File Sizes.
 * @param {number} bytes Bytes in Number
 */
export const humanFileSize = (bytes) => {
  let BYTES = bytes;
  const thresh = 1024;

  if (Math.abs(BYTES) < thresh) { return `${BYTES} B`; } const units = ["kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"]; let u = -1; const r = 10 ** 1; do { BYTES /= thresh; u += 1; } while (Math.round(Math.abs(BYTES) * r) / r >= thresh && u < units.length - 1);

  return `${BYTES.toFixed(1)} ${units[u]}`;
};

// Example
console.log(humanFileSize(456465465)); // 456.5 MB

setLocalItem() & getLocalItem()

让 LocalStorage 具有过期时间。

/**
 * Caching values with expiry date to the LocalHost.
 * @param {string} key Local Storage Key
 * @param {any} value Local Storage Value
 * @param {number} ttl Time to live (Expiry Date in MS)
 */
export const setLocalItem = (key, value, ttl = duration.month) => {
  const now = new Date();
  // `item` is an object which contains the original value
  // as well as the time when it's supposed to expire
  const item = {
    value,
    expiry: now.getTime() + ttl,
  };
  localStorage.setItem(key, JSON.stringify(item));
};

/**
 * Getting values with expiry date from LocalHost that stored with `setLocalItem`.
 * @param {string} key Local Storage Key
 */
export const getLocalItem = (key) => {
  const itemStr = localStorage.getItem(key);
  // if the item doesn't exist, return null
  if (!itemStr) {
    return null;
  }
  const item = JSON.parse(itemStr);
  const now = new Date();
  // compare the expiry time of the item with the current time
  if (now.getTime() > item.expiry) {
    // If the item is expired, delete the item from storage
    // and return null
    localStorage.removeItem(key);
    return null;
  }
  return item.value;
};

getTimes()

你是否有一个 DDL，它每 n 分钟显示一天的时间?用这个函数。

/**
 * Getting an Array of Times + "AM" or "PM".
 * @param {number} minutesInterval
 * @param {number} startTime 
 */
export const getTimes = (minutesInterval = 15, startTime = 60) => {
  const times = []; // time array
  const x = minutesInterval; // minutes interval
  let tt = startTime; // start time
  const ap = ["AM", "PM"]; // AM-PM

  // loop to increment the time and push results in array
  for (let i = 0; tt < 24 * 60; i += 1) {
    const hh = Math.floor(tt / 60); // getting hours of day in 0-24 format
    const mm = tt % 60; // getting minutes of the hour in 0-55 format
    times[i] = `${`${hh === 12 ? 12 : hh % 12}`.slice(-2)}:${`0${mm}`.slice(-2)} ${
      ap[Math.floor(hh / 12)]
    }`; // pushing data in array in [00:00 - 12:00 AM/PM format]
    tt += x;
  }
  return times;
};

// Example
console.log(getTimes());
/* [
    "1:00 AM",
    "1:15 AM",
    "1:30 AM",
    "1:45 AM",
    "2:00 AM",
    "2:15 AM",
    "2:30 AM",
    // ....
    ]
*/

formatNumber()

/**
 * Format numbers with separators.
 * @param {number} num
 */
export const formatNumber = (num) => num.toLocaleString();

// Example
console.log(formatNumber(78899985)); // 78,899,985

我们还可以添加其他选项来获取其他数字格式，如货币、距离、权重等。

export const toEGPCurrency = (num) =>
  num.toLocaleString("ar-EG", { style: "currency", currency: "EGP" });

export const toUSDCurrency = (num) =>
  num.toLocaleString("en-US", { style: "currency", currency: "USD" });

console.log(toUSDCurrency(78899985)); // $78,899,985.00
console.log(toEGPCurrency(78899985)); // ٧٨٬٨٩٩٬٩٨٥٫٠٠ ج.م.

getScreenWidth()

获取一个表示屏幕宽度的字符串。

/**
 * Detect screen width and returns a string representing the width of the screen.
 */
export const getScreenWidth = () => {
  const screenWidth = window.screen.width;
  if (screenWidth <= 425) return "mobile";
  if (screenWidth <= 768) return "tablet";
  if (screenWidth <= 1024) return "laptopSm";
  if (screenWidth <= 1440) return "laptopLg";
  if (screenWidth <= 2560) return "HD";
  return screenWidth;
};

检查数组中的每个元素是否存在于另一个数组中。

export const containsAll = (baseArr, arr) => {
  let all = false;

  for (let i = 0; i < arr.length; i += 1) {
    if (baseArr.includes(arr[i])) {
      all = true;
    } else {
      all = false;
      return all;
    }
  }

  return all;
};

toFormData()

每当我需要向服务器发送文件时，我就使用这个函数。

/**
 * Convert Objects to Form Data Format.
 * @param {object} obj
 */
export const toFormData = (obj) => {
  const formBody = new FormData();
  Object.keys(obj).forEach((key) => {
    formBody.append(key, obj[key])
  })
  
  return formBody;
}