Say I have two arrays
["a", "b", "c"]
["c", "a", "b"]
What is the best way to compare these two arrays and see if they are equal (they should come as equal for the above scenario)
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possible duplicat of stackoverflow.com/questions/13523611/…user2009750– user20097502014-04-02 13:17:15 +00:00Commented Apr 2, 2014 at 13:17
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Clearly a duplicate; the only missing link is pre-sorting both compared arrays first.raina77ow– raina77ow2014-04-02 13:19:09 +00:00Commented Apr 2, 2014 at 13:19
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@pronox That solution doesn't work > var arr1 = ["a","b","c"]; undefined > var arr2 = ["c","a","b"]; undefined > if (arr1.length == arr2.length ... && arr1.every(function(u, i) { ..... return u === arr2[i]; ..... }) ... ) { ... console.log(true); ... } else { ... console.log(false); ... } falsebluesman– bluesman2014-04-02 13:22:04 +00:00Commented Apr 2, 2014 at 13:22
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then how is it marked accepted and up voted few times, let me check iuser2009750– user20097502014-04-02 15:21:17 +00:00Commented Apr 2, 2014 at 15:21
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@bluesman its workinguser2009750– user20097502014-04-02 15:29:24 +00:00Commented Apr 2, 2014 at 15:29
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2 Answers
function compareArrays(array1, array2) {
array1 = array1.slice();
array2 = array2.slice();
if (array1.length === array2.length) { // Check if the lengths are same
array1.sort();
array2.sort(); // Sort both the arrays
return array1.every(function(item, index) {
return item === array2[index]; // Check elements at every index
}); // are the same
}
return false;
}
console.assert(compareArrays(["a", "b", "c"], ["c", "a", "b"]) === true);
12 Comments
Esailija
You are changing the arrays as a side effect
thefourtheye
@Esailija Fixed it :) Please check now.
Esailija
Sure but why not
return array1.length === array2.length && array1.every(item => array2.indexOf(item) > -1); much simpler and faster :Pthefourtheye
@Esailija I test the solutions before I post them. That is ES6 and I couldn't test that :(
thefourtheye
@Esailija Apart from that, technically that is O(N^2), I believe
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You can try with _.difference
var diff = _(array1).difference(array2);
if(diff.length > 0) {
// There is a difference
}
this will not work because different returns diff from first array. _.difference(['a'] ,['a','b']) is 0 but two array is not equal.
