问在javascript中最简单的数组交集？

.filter 元素的第一个数组也包含在第二个数组中！

array1.filter((n) => array2.includes(n))

Destructive seems simplest, especially if we can assume the input is sorted:

/* destructively finds the intersection of

* two arrays in a simple fashion.

*

* PARAMS

* a - first array, must already be sorted

* b - second array, must already be sorted

*

* NOTES

* State of input arrays is undefined when

* the function returns. They should be

* (prolly) be dumped.

*

* Should have O(n) operations, where n is

* n = MIN(a.length, b.length)

*/

function intersection_destructive(a, b)

{

var result = [];

while( a.length > 0 && b.length > 0 )

{

if (a[0] < b[0] ){ a.shift(); }

else if (a[0] > b[0] ){ b.shift(); }

else /* they're equal */

{

result.push(a.shift());

b.shift();

}

}

return result;

}

Non-destructive has to be a hair more complicated, since we’ve got to track indices:

/* finds the intersection of

* two arrays in a simple fashion.

*

* PARAMS

* a - first array, must already be sorted

* b - second array, must already be sorted

*

* NOTES

*

* Should have O(n) operations, where n is

* n = MIN(a.length(), b.length())

*/

function intersect_safe(a, b)

{

var ai=0, bi=0;

var result = [];

while( ai < a.length && bi < b.length )

{

if (a[ai] < b[bi] ){ ai++; }

else if (a[ai] > b[bi] ){ bi++; }

else /* they're equal */

{

result.push(a[ai]);

ai++;

bi++;

}

}

return result;

}