用javascript实现数组交叉的最简单、无库代码是什么?我想写

intersection([1,2,3], [2,3,4,5])

并获得

[2, 3]

当前回答

希望这有助于所有版本。

function diffArray(arr1, arr2) {
  var newArr = [];

  var large = arr1.length>=arr2.length?arr1:arr2;
  var small = JSON.stringify(large) == JSON.stringify(arr1)?arr2:arr1;
  for(var i=0;i<large.length;i++){
    var copyExists = false; 
    for(var j =0;j<small.length;j++){
      if(large[i]==small[j]){
        copyExists= true;
        break;
      }
    }
    if(!copyExists)
      {
        newArr.push(large[i]);
      }
  }

  for(var i=0;i<small.length;i++){
    var copyExists = false; 
    for(var j =0;j<large.length;j++){
      if(large[j]==small[i]){
        copyExists= true;
        break;
      }
    }
    if(!copyExists)
      {
        newArr.push(small[i]);
      }
  }


  return newArr;
}

其他回答

function intersection(A,B){
var result = new Array();
for (i=0; i<A.length; i++) {
    for (j=0; j<B.length; j++) {
        if (A[i] == B[j] && $.inArray(A[i],result) == -1) {
            result.push(A[i]);
        }
    }
}
return result;
}

使用jQuery:

var a = [1,2,3];
var b = [2,3,4,5];
var c = $(b).not($(b).not(a));
alert(c);

该函数利用字典的强大功能,避免了N^2问题。每个数组只循环一次,第三次更短的循环返回最终结果。 它还支持数字、字符串和对象。

function array_intersect(array1, array2) 
{
    var mergedElems = {},
        result = [];

    // Returns a unique reference string for the type and value of the element
    function generateStrKey(elem) {
        var typeOfElem = typeof elem;
        if (typeOfElem === 'object') {
            typeOfElem += Object.prototype.toString.call(elem);
        }
        return [typeOfElem, elem.toString(), JSON.stringify(elem)].join('__');
    }

    array1.forEach(function(elem) {
        var key = generateStrKey(elem);
        if (!(key in mergedElems)) {
            mergedElems[key] = {elem: elem, inArray2: false};
        }
    });

    array2.forEach(function(elem) {
        var key = generateStrKey(elem);
        if (key in mergedElems) {
            mergedElems[key].inArray2 = true;
        }
    });

    Object.values(mergedElems).forEach(function(elem) {
        if (elem.inArray2) {
            result.push(elem.elem);
        }
    });

    return result;
}

如果有无法解决的特殊情况,仅通过修改generateStrKey函数就可以解决。这个函数的诀窍在于,它根据类型和值唯一地表示每个不同的数据。


这个变体有一些性能改进。在任何数组为空的情况下避免循环。它还首先遍历较短的数组,因此如果它在第二个数组中找到了第一个数组的所有值,则退出循环。

function array_intersect(array1, array2) 
{
    var mergedElems = {},
        result = [],
        firstArray, secondArray,
        firstN = 0, 
        secondN = 0;

    function generateStrKey(elem) {
        var typeOfElem = typeof elem;
        if (typeOfElem === 'object') {
            typeOfElem += Object.prototype.toString.call(elem);
        }
        return [typeOfElem, elem.toString(), JSON.stringify(elem)].join('__');
    }

    // Executes the loops only if both arrays have values
    if (array1.length && array2.length) 
    {
        // Begins with the shortest array to optimize the algorithm
        if (array1.length < array2.length) {
            firstArray = array1;
            secondArray = array2;
        } else {
            firstArray = array2;
            secondArray = array1;            
        }

        firstArray.forEach(function(elem) {
            var key = generateStrKey(elem);
            if (!(key in mergedElems)) {
                mergedElems[key] = {elem: elem, inArray2: false};
                // Increases the counter of unique values in the first array
                firstN++;
            }
        });

        secondArray.some(function(elem) {
            var key = generateStrKey(elem);
            if (key in mergedElems) {
                if (!mergedElems[key].inArray2) {
                    mergedElems[key].inArray2 = true;
                    // Increases the counter of matches
                    secondN++;
                    // If all elements of first array have coincidence, then exits the loop
                    return (secondN === firstN);
                }
            }
        });

        Object.values(mergedElems).forEach(function(elem) {
            if (elem.inArray2) {
                result.push(elem.elem);
            }
        });
    }

    return result;
}

如果你需要让它处理交叉多个数组:

Const intersect = (a1, a2,…rest) => { Const a12 = a1。过滤器(value => a2.includes(value)) 如果休息。长度=== 0){返回a12;} 回归相交(a12,…rest); }; console.log(相交([1、2、3、4、5],[1,2],[1、2、3、4、5],[2 10 1]))

“filter”和“indexOf”在IE中的Array上不支持。这个怎么样:

var array1 = [1, 2, 3];
var array2 = [2, 3, 4, 5];

var intersection = [];
for (i in array1) {
    for (j in array2) {
        if (array1[i] == array2[j]) intersection.push(array1[i]);
    }
}