Heavy relatively simple to

Ready to test code:

Array.from of arr1 = const ( new new the Array (100000), (Item, index) => {
   return index; 
}); 
const arr2 is = Array.from ( new new the Array (50000), (Item, index) => {
   return index 2 * ; 
}); 
the console.log ( 'start test' ); 
const start = new new a Date () the getTime ();. 
DISTINCT (of arr1, arr2 is); // method to weight 
const End = new new a Date () .getTime ( ); 
the console.log ( 'end of the test' ); 
the console.log ( 'test time' + (end - start) / 1000 + 's');

一：filter + indexOf

function distinct(arr1, arr2) {
  console.log('filter + indexOf');
  const arr = [...arr1, ...arr2];
  return arr.filter((item, index) => {
    return arr.indexOf(item) === index;
  });
}

Effect: Time 11s

II: double loop, delete (splice) duplicates

function distinct(a, b) {

　　the console.log ( 'double loop for');

  ARR const = a.concat (B);
   for (I = 0 the let, len = arr.length; I <len; I ++ ) {
     for (J = I + the let. 1; J <len; J ++ ) {
       IF (ARR [ I] == ARR [j]) { 
        arr.splice (j, . 1 );
         // splice will change the length of the array, so to the length of the array index j and len minus one 
        len-- ; 
        j - ; 
      } 
    } 
  } 
  return ARR 
}

Effect: 22s

 三、includes + push

function distinct(arr1, arr2) {
  console.log('includes + push新数组');
  const arr = [...arr1, ...arr2];
  const result = [];
  for (item of arr) {
    !result.includes(item) && result.push(item);
  }
  return result;
}

Effect: 11s

 

Fourth, the first sort (sort), then compare the two approaching

function distinct(arr1, arr2) {
  console.log('先排序, 比较临近的2个 然后push');
  let arr = [...arr1, ...arr2];
  arr = arr.sort((a, b) => {return a - b});
  const result = [];
  for (let i = 0, len = arr.length; i < len; i++) {
    (arr[i] !== arr[i + 1]) && result.push(arr[i]);
  }
  return result;
}

Effect: 0.03s

Fourth, use set

function distinct(arr1, arr2) {
  console.log('使用set');
  const arr = [...arr1, ...arr2];
  return Array.from(new Set(arr));
}

Effect: 0.04s

Five, for recycling with the use of the object, and then push

function distinct(arr1, arr2) {
  console.log('for循环配合对象使用，然后push');
  const arr = [...arr1, ...arr2];
  const len = arr.length;
  const obj = {};
  const result = [];
  for (let i = 0; i < len; i++){
    if (!obj[i]) {
      result.push(arr[i]);
      obj[i] = 1;
    }
  }
  return result;
}

Effect: 0.03s

六、reduce

function distinct(arr1, arr2) {
  console.log('reduce');
  const arr = [...arr1, ...arr2];
  arr.reduce((prev, cur) => {
    if (!prev.includes(cur)) {
      return [...prev, cur];
    } else {
      return prev;
    }
  }, []);
}

Effect: 110s