export function getQueryString(name) {
  let reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i")
  let r = window.location.search.substr(1).match(reg)
  if (r != null) {
    return window.decodeURIComponent(r[2])
  }
  return null
}

export function debounce(fn, delay) {
  let timer; // 定时器
  return function (...args) { // 形成闭包
    // args 为函数调用时传的参数。
    let context = this;
    timer && clearTimeout(timer); // 当函数再次执行时，清除定时器，重新开始计时
    // 利用定时器，让指定函数延迟执行。
    timer = setTimeout(function () {
      // 执行传入的指定函数，利用apply更改this绑定和传参
      fn.apply(context, args);
    }, delay)
  }
}

export function throttle(fn, thresh) {
  var timeout
  var start = new Date;
  var threshhold = thresh || 500
  return function () {

    var context = this, args = arguments, curr = new Date() - 0

    clearTimeout(timeout)//总是干掉事件回调
    if (curr - start >= threshhold) {
      fn.apply(context, args) //只执行一部分方法，这些方法是在某个时间段内执行一次
      start = curr
    } else {
      // 让方法在脱离事件后也能执行一次
      timeout = setTimeout(function () {
        fn.apply(context, args)
      }, threshhold);
    }
  }
}

export function setStorage(key, value) {
  return localStorage.setItem(key, JSON.stringify(value));
}

export function getStorage(key) {
  const item = localStorage.getItem(key);
  try {
    return item ? JSON.parse(item) : '';
  } catch (e) {
    return item;
  }
}

export function guid() {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
    var r = Math.random() * 16 | 0, v = c == 'x' ? r : (r & 0x3 | 0x8);
    return v.toString(16);
  });
}

export function scaleNumber(num) {
    let length = num.toString().split('.')[1].length;
    
    let scale = '1';
    
    for(let i = 0; i < length; i++) {
        scale += '0';
    }

    let val = num * scale;
    return {
      val,
      scale
    };
}

export function getBit (value) {
  const reg = /([0-9]+\.[0-9]{4})[0-9]*/;
  if(value) {
    let str = value.toString();
    str = str.replace(reg,"$1");
    return str;
  } else {
    return value;
  }
}