检查JavaScript中两个数组的值是否相同/相等的最佳方法

Question

What is the best way to check if two arrays have the same/equal values (in any order) in JavaScript?

These values are just a primary keys of database entities, so they always will be different

const result = [1, 3, 8, 77]
const same = [8, 3, 1, 77]
const diff = [8, 3, 5, 77]

areValuesTheSame(result, same) // true
areValuesTheSame(result, diff) // false

How should areValuesTheSame method look like?

PS This question looks like a duplicate but I didn't find anything relative to Javascript.

Answer 1

I'm making the following assumptions:

• The arrays only contain numbers.
• You don't care about the order of the elements; rearranging the arrays is OK.

Under those conditions we can simply convert each array to a canonical string by sorting it and joining the elements with eg a space. Then (multi-)set equality boils down to simple string equality.

 function areValuesTheSame(a, b) { return a.sort().join(' ') === b.sort().join(' '); } const result = [1, 3, 8, 77]; const same = [8, 3, 1, 77]; const diff = [8, 3, 5, 77]; console.log(areValuesTheSame(result, same)); console.log(areValuesTheSame(result, diff)); 

This is probably the laziest / shortest approach.

Answer 2

You could count all elements with a Map (this is type save) up for the one array and down for the other and check if all items have a final count of zero.

 function haveSameValues(a, b) { const count = d => (m, v) => m.set(v, (m.get(v) || 0) + d) return Array .from(b.reduce(count(-1), a.reduce(count(1), new Map)).values()) .every(v => v === 0); } const result = [1, 3, 8, 77] const same = [8, 3, 1, 77] const diff = [8, 3, 5, 77] console.log(haveSameValues(result, same)); // true console.log(haveSameValues(result, diff)); // false 

Answer 3

Try this:

 const result = [1, 3, 8, 77] const same = [8, 3, 1, 77] const diff = [8, 3, 5, 77] const areValuesTheSame = (a,b) => (a.length === b.length) && Object.keys(a.sort()).every(i=>a[i] === b.sort()[i]) console.log(areValuesTheSame(result, same)) // true console.log(areValuesTheSame(result, diff)) // false