How to compare two array and alert the result?

Question

I have two simple arrays:

var arr_must_exist = ["1","2","3"]; var arr_created = ["2","4","7","8"]; //This is varies depend of the array created.

So, if arr_created is like the example there should be an alert like Your choice must contain 1 and 3

Example:

arr_created = ["2","4","7","8"]; alert(`Your choice must contain 1 and 3`) arr_created = ["2","3","7","8"]; alert(`Your choice must contain 1`) arr_created = ["4","5","7","8"]; alert(`Your choice must contain 1, 2 and 3`) arr_created = ["1","2","9","3"]; alert(`Your choice is valid`)

I use $.each but it's only check the array. Not comparing them.

$.each(arr_is_must_exist , function(index, val_must_exist) { $.each(arr_is_exist_in_table , function(index, val_is_exist) { if(val_must_exist != val_is_exist){ alert("Your choice must contain 1,2,3"); } }); });

I look here but there is not accepted answer. I use IE and mozilla (it's for local user)

Possible duplicate of What is the fastest or most elegant way to compute a set difference using Javascript arrays? — Kevin Ji
– Kevin Ji, Commented Dec 7, 2017 at 4:26

Khiem Tran · Accepted Answer · 2017-12-07 04:14:51Z

9

You can find the array of missing items like below:

var arr_must_exist = ["1","2","3"]; var arr_created = ["2","4","7","8"]; var missing = arr_must_exist.filter(e => arr_created.indexOf(e) < 0); console.log(missing);

answered Dec 7, 2017 at 4:14

Khiem Tran

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2 Comments

Manikant Gautam Over a year ago

alert is missing.

Khiem Tran Over a year ago

I think the author can do that part.

programtreasures · Accepted Answer · 2017-12-07 04:26:34Z

You can do by simple javascript with your log message

var arr_must_exist = ["1","2","3"]; var arr_created = ["2","4","7","8"]; //This is varies depend of the array created. var numberNotAvailable = []; for(var i = 0; i<arr_must_exist.length; i++){ console.log(arr_created.indexOf(arr_must_exist[i])); if(arr_created.indexOf(arr_must_exist[i]) < 0){ console.log(arr_must_exist[i] + ' added'); numberNotAvailable.push(arr_must_exist[i]) } } var logMessage ; if(numberNotAvailable.length == 0){ logMessage = 'Your choice is valid'; } else if(numberNotAvailable.length == 1){ logMessage = 'Your choice must contain ' + numberNotAvailable[0]; } else if(numberNotAvailable.length == 2){ logMessage = 'Your choice must contain ' + numberNotAvailable[0] + ' and ' + numberNotAvailable[1]; } else if(numberNotAvailable.length > 2){ logMessage = 'Your choice must contain ' + fruits.join(); } console.log(logMessage);

brk · Accepted Answer · 2017-12-07 04:16:33Z

It can be done in javascript using forEach & join array methods

var arr_must_exist = ["1", "2", "3"]; var arr_created = ["2", "4", "7", "8"]; // An array to store the elements which are not in arr_created var missingElements = []; // looping over arr_must_exist and checking if // element is present in arr_created using indexOf arr_must_exist.forEach(function(item) { if (arr_created.indexOf(item) === -1) { // if not push the element in the array missingElements.push(item) } }) // if missingElements length is greater than 1 mean if it contain // any element then join all the element ,create string with a comma //separator if (missingElements.length > 0) { alert(missingElements.join(',')) }

cdoshi · Accepted Answer · 2017-12-07 04:35:31Z

You will have to write a function that does the comparing and stores the difference in an array

var arr_must_exist = ["1","2","3"]; var arr_created = ["2","4","7","8"]; var diff = []; arr_must_exist.forEach(function(value){ if(arr_created.indexOf(value) < 0) { diff.push(value); } }); var str = ''; if(diff.length) { var str = 'Your choice must contain '; diff.forEach(function(value, index) { str += ((index+1 == diff.length) ? ' and ' + value : value) }); } else { str = 'Your choice is valid'; } alert(str);

user8897421 · Accepted Answer · 2017-12-07 04:38:46Z

This uses a Set to check for the existence of each item in arr_must_exist.

It also uses a regex to get the "and" or the "," right, and a template literal to put the message together.

const arr_must_exist = ["1","2","3"]; function getMsg(arr_created) { const set = new Set(arr_created); const m = arr_must_exist.filter(s => !set.has(s)) .join(", ") .replace(/, ([^,]+)$/, " and $1"); return `Your choice ${m ? "must contain " + m : "is valid"}`; } console.log(getMsg(["2","4","7","8"])); console.log(getMsg(["2","3","7","8"])); console.log(getMsg(["4","5","7","8"])); console.log(getMsg(["1","2","9","3"]));

A.D. · Accepted Answer · 2017-12-07 04:42:32Z

There various way to doing so the set of limited number of practice may you use. Like

By $.map() function
By $.filter() function
By array compare with multiple for Loops

Code Examples :

<script src="https://code.jquery.com/jquery-1.10.2.js"></script> <script> var arr_must_exist = ["1","2","3"]; var arr_created = ["2","4","7","8"]; var noElement =[]; // This Example contains the `$.map()` function to accomplish the task. $.map(arr_must_exist, function(el){ if($.inArray(el, arr_created) < 0) { noElement.push(el); return null; } else { return el; } return $.inArray(el, arr_created) < 0 ? null : el; }); if(noElement.length <= 0) { console.log("Your choice is valid"); } else { console.log("Your choice must contain "+noElement); } //This example contain the `$.filter()` check; $checkarray = arr_must_exist.filter(e => arr_created.indexOf(e) < 0); if($checkarray.length == 0) { console.log("Your choice is valid"); } else { console.log("Your choice must contain "+ $checkarray); } </script>

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