JavaScript实用工具函数开发技巧

阻止冒泡事件

export const stopPropagation = (e) => { 
    e = e || window.event; 
    if(e.stopPropagation) {    // W3C阻止冒泡方法 
        e.stopPropagation(); 
    } else { 
        e.cancelBubble = true; // IE阻止冒泡方法 
    } 
} 

防抖函数

export const debounce = (fn, wait) => {
  let timer = null;

  return function() {
    let context = this,
        args = arguments;

    if (timer) {
      clearTimeout(timer);
      timer = null;
    }

    timer = setTimeout(() => {
      fn.apply(context, args);
    }, wait);
  };
}

节流函数

export const throttle = (fn, delay) => {
  let curTime = Date.now();

  return function() {
    let context = this,
        args = arguments,
        nowTime = Date.now();

    if (nowTime - curTime >= delay) {
      curTime = Date.now();
      return fn.apply(context, args);
    }
  };
}

数据类型判断

export const getType = (value) => {
  if (value === null) {
    return value + "";
  }
  // 判断数据是引用类型的情况
  if (typeof value === "object") {
    let valueClass = Object.prototype.toString.call(value),
      type = valueClass.split(" ")[1].split("");
    type.pop();
    return type.join("").toLowerCase();
  } else {
    // 判断数据是基本数据类型的情况和函数的情况
    return typeof value;
  }
}

对象深拷贝

export const deepClone = (obj, hash = new WeakMap() => {
  // 日期对象直接返回一个新的日期对象
  if (obj instanceof Date){
    return new Date(obj);
  } 
  //正则对象直接返回一个新的正则对象     
  if (obj instanceof RegExp){
    return new RegExp(obj);     
  }
  //如果循环引用,就用 weakMap 来解决
  if (hash.has(obj)){
    return hash.get(obj);
  }
  // 获取对象所有自身属性的描述
  let allDesc = Object.getOwnPropertyDescriptors(obj);
  // 遍历传入参数所有键的特性
  let cloneObj = Object.create(Object.getPrototypeOf(obj), allDesc)
  
  hash.set(obj, cloneObj)
  for (let key of Reflect.ownKeys(obj)) { 
    if(typeof obj[key] === 'object' && obj[key] !== null){
        cloneObj[key] = deepClone(obj[key], hash);
    } else {
        cloneObj[key] = obj[key];
    }
  }
  return cloneObj
}

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