Exploring the process of obtaining a collection of JSON sub-items and using Angular's method for finding a match within an array

Question

Exploring the process of obtaining a collection of JSON sub-items and using Angular's method for finding a match within an array

Question 1

In my program, I am receiving a JSON object called scope.tagSet, which has the structure shown below.

{ Tags : [
           {"TagID" : "ID1" , "TagName" : "Name1"},
           {"TagID" : "ID2" , "TagName" : "Name2"},
           {"TagID" : "ID3" , "TagName" : "Name3"}
         ]
}

Within an angular directive, I am creating an array of all the values in TagName like this.

for(var i= 0; i < scope.tagSet.Tags.length; i++){
                          scope.tagNames[i] = scope.tagSet.Tags[i].TagName;
}

Is there only one method to iterate through and assign each value? Or is there a more efficient way to achieve this task?

Question 2

Now, if I have an array named tagNames[], my next task is to search for a specific variable varString within the tagNames[] array and return true or false based on its existence. I understand that using

scope.tagNames.indexOf(varString)

will result in -1 if there are no matches,

but is this considered the appropriate angular approach? Are these methods generally viewed as best practices?

javascript json angularjs

Answer 1

Answer №1

To create a lookup list, you can utilize JavaScript and create an object for this purpose:

function arrayToLookup(a, key) {
    var o = {};
    for (var i = a.length; i--;) {
        o[a[i][key]] = true;
    }
    return o;
}

Here is how you can use it:

var lookupList = arrayToLookup(scope.tagSet.Tags, "TagName");

You can then easily check if a value is available in the lookup list like so:

lookupList["Name1"]; // returns true

Answer 2

To create a lookup list, you can utilize JavaScript and create an object for this purpose:

function arrayToLookup(a, key) {
    var o = {};
    for (var i = a.length; i--;) {
        o[a[i][key]] = true;
    }
    return o;
}

Here is how you can use it:

var lookupList = arrayToLookup(scope.tagSet.Tags, "TagName");

You can then easily check if a value is available in the lookup list like so:

lookupList["Name1"]; // returns true

Answer 3

Answer №2

What motivates your interest in following the angular approach so diligently? Have you considered the possibility of someday moving away from angular entirely? It seems more probable to switch from angular while keeping JavaScript as a foundation. Here's a simple example using JavaScript:

const tags = tagData.map(tag => tag.tagName);

You can then utilize the indexOf method as initially proposed.

Answer 4

What motivates your interest in following the angular approach so diligently? Have you considered the possibility of someday moving away from angular entirely? It seems more probable to switch from angular while keeping JavaScript as a foundation. Here's a simple example using JavaScript:

const tags = tagData.map(tag => tag.tagName);

You can then utilize the indexOf method as initially proposed.

Answer 5

Answer №3

If you're looking to see if a specific item is in an array, consider utilizing the angular-filtermodule:

$scope.items = [
    {"TagID" : "ID1" , "TagName" : "Name1"},
    {"TagID" : "ID2" , "TagName" : "Name2"},
    {"TagID" : "ID3" , "TagName" : "Name3"}
]

// returns true
$scope.Name1 = $filter('contains')($scope.items,'TagName == "Name1"');
// returns false
$scope.Name4 = $filter('contains')($scope.items,'TagName == "Name4"');

Take a look at this working example on plunker

Answer 6

If you're looking to see if a specific item is in an array, consider utilizing the angular-filtermodule:

$scope.items = [
    {"TagID" : "ID1" , "TagName" : "Name1"},
    {"TagID" : "ID2" , "TagName" : "Name2"},
    {"TagID" : "ID3" , "TagName" : "Name3"}
]

// returns true
$scope.Name1 = $filter('contains')($scope.items,'TagName == "Name1"');
// returns false
$scope.Name4 = $filter('contains')($scope.items,'TagName == "Name4"');

Take a look at this working example on plunker

Answer 7

Answer №4

Here is a helpful snippet for you:

let newTagArray=[];
    angular.forEach(scope.tagSet.Tags, function(value, key) {
       newTagArray[i] = value.TagName;
    });
scope.newTagNames=newTagArray;

Answer 8

Here is a helpful snippet for you:

let newTagArray=[];
    angular.forEach(scope.tagSet.Tags, function(value, key) {
       newTagArray[i] = value.TagName;
    });
scope.newTagNames=newTagArray;

Exploring the process of obtaining a collection of JSON sub-items and using Angular's method for finding a match within an array

Question 1

Question 2

Answer №1

Answer №2

Answer №3

Answer №4

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