排序方法、其他常用的方法

快速排序

function fast (arr) {
    if (arr.length <= 1) {
        return arr
    }
    let left = []
    let right = []
    let p = arr.splice(0, 1)[0]
    for (let i = 0, l = arr.length; i < l; i++) {
        if (p > arr[i]) {
            left.push(arr[i])
        } else {
            right.push(arr[i])
        }
    }
    return [].concat(fast(left), [p], fast(right))
}

冒泡排序

function pubble (arr) {
    if (arr.length <= 1) {
        return arr
    }
    for (let i = 0, l = arr.length; i < l - 1; i++) {
        for (let j = i; j < l; j++) {
            if (arr[i] > arr[j]) {
                let temp = arr[i]
                arr[i] = arr[j]
                arr[j] = temp
            }
        }
    }
    return arr
}

插入排序

function insert (arr) {
    for (let i = 1, l = arr.length; i < l; i++) {    
        let temp = arr[i]
        let j = i - 1
        while (j >= 0 && arr[j] > temp) {
            arr[j + 1] = arr[j]
            j--
        }
        arr[j + 1] = temp
    }
    return arr
}

选择排序

function selection (arr) {
    let l = arr.length
    for (let i = 0; i < l - 1; i++) {
        let minIndex = i
        for (let j = i; j < l; j++) {
            if (arr[j] < arr[minIndex]) {
                minIndex = j
            }
        }
        let temp = arr[i]
        arr[i] = arr[minIndex]
        arr[minIndex] = temp
    }
    return arr
}

经典阶乘函数

function factorial(num){
    if(num<=1){
        return 1;
    }else{
        return num*arguments.callee(num-1);
    }
}
console.log(factorial(4));//24

函数节流

delayFunc(fn, interval) {
  let _self = fn;
  let timer;
  let firstTime = true;
  return function () {
      let args = arguments;
      let _me = this;
      if (firstTime) {
          _self.apply(_me, args);
          firstTime = false;
          return false;
      }
      if (timer) {
          return false;
      }
      timer = setTimeout(function () {
          clearTimeout(timer);
          timer = null;
          _self.apply(_me, args);
      }, interval || 500);
  };
},