lodash笨方法实现之路

1. // _.chunk(array, [size=1])
   function chunk(array, num) {
   var arr = []
   for (var i = 0; i < array.length; i += num) {
   arr.push(array.slice(i, i + num))
   }
   return arr
   }
   var arr = [1, 2, 3, 4, 5]
   console.log(chunk(arr, 0))

   ·源码

2. function chunk(array, size, guard) {
         if ((guard ? isIterateeCall(array, size, guard) : size === undefined)) {
           size = 1;
         } else {
           size = nativeMax(toInteger(size), 0);
         }
         var length = array == null ? 0 : array.length;
         if (!length || size < 1) {
           return [];
         }
         var index = 0,
             resIndex = 0,
             result = Array(nativeCeil(length / size));
   
         while (index < length) {
           result[resIndex++] = baseSlice(array, index, (index += size));
         }
         return result;
       }
   

    

3. // _.compact(array)
   // Creates an array with all falsey values removed. The values false, null, 0, "", undefined, and NaN are falsey.
   function compact(array) {
       var arr = []
       for (var i = 0; i < array.length; i++) {
           if (array[i]) {
               arr.push(array[i])
           }
       }
       return arr
   }
   var arr = [1, 2, 3, 4, 5, false, NaN, 0, 99]
   console.log(compact(arr))