CODEWITHSUNDEEP
javascriptjqueryarrays
ashura91
ashura91

Reputation: 441

How to match arrays and show the one that are NOT in the array?

I have a two array with with different values. I'd like to match the arrays and spearate the values that is not match. It's my current script:

var array_must_exist = ['4','5'];
var array_to_compare = [{"NO": "1"},{"NO": "2"},{"NO": "5"},{"NO": "7"}];

$.each(array_to_compare, function(i, result){   

   var arr = jQuery.grep(array_must_exist, function(value) {

                return value != result.NO;
             });

    alert(arr);
});

When array_must_exist is in array_to_compare the arr returns 5 and 4. How to alert the one is not in the array?

if array_to_compare = [{"NO": "1"},{"NO": "4"}]; the alert is 5 is missing
if array_to_compare = [{"NO": "5"},{"NO": "6"},{"NO": "3"}]; the alert is 4 is missing
if array_to_compare = [{"NO": "4"},{"NO": "5"},{"NO": "6"},{"NO": "7"}]; the alert is Nothing is missing

Upvotes: 0

Views: 50

Answers (2)

user9366559
user9366559

Reputation:

You just need to .filter() the array_must_exist array down to ones where .some() is not able to locate a match in array_to_compare.

var array_must_exist = ['4','5'];
var array_to_compare = [{"NO": "1"},{"NO": "2"},{"NO": "5"},{"NO": "7"}];


var missing = array_must_exist.filter(n =>   // `n` is the current number.
  !array_to_compare.some(obj => obj.NO == n) // See if `n` is in any object.
);


console.log("missing:", missing.length ? missing : "None")

So for each item in array_must_exist, if "not some" (or in other words "none") are found in array_to_compare, that value will be included in the result. If the result is empty, then all were found.

Upvotes: 2

Ele
Ele

Reputation: 33726

You can use the functions reduce and findIndex to extract the missing values.

function compare(array_must_exist, array_to_compare) {
  return array_must_exist.reduce((a, c) => {
    if (array_to_compare.findIndex((a) => a.NO === c) === -1) a.push(c);
    return a;
  }, []);
}

console.log('Missing:', compare(['4','5'], [{"NO": "1"},{"NO": "2"},{"NO": "5"},{"NO": "7"}]).join());
console.log('Missing:', compare(['4','5'], [{"NO": "4"}]).join());
console.log('Missing:', compare(['4','5'], [{"NO": "4"}, {"NO": "5"}]).join());
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 1

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