Why is it that I cannot use the .get method on JSON data? And what is the best way to convert JSON into a map?

Question

Why is it that I cannot use the .get method on JSON data? And what is the best way to convert JSON into a map?

I'm currently in the process of creating a test for a function that accepts a map as an argument,

Under normal circumstances when the code is executed outside of a test, the parameter would appear like this (when calling toString):

Map { "id": "jobs", "label": "Jobs", "nodeType": "ROOT", "childNodesURI": "jobs?owner=*", "childIds": List [], "isFetchingChildren": false, "isToggled": true, "jobName": "" }

var node = {
                id: "jobs", 
                label: "JES Jobs", 
                nodeType: "ROOT", 
                childNodesURI: "jobs?owner=*", 
                childIds: [],
                isFetchingChildren: false, 
                isToggled: true, 
                jobName: "" };
                console.log(node.get("id"));

Upon calling node.get("id"), I encounter the error message "TypeError: node.get is not a function"

I suspect this issue arises because there is no .get() function for a JSON object, although I'm not entirely certain... If my assumption is correct, how can I convert or initialize the JSON as a map?

javascript json

Answer 1

Answer №1

What you're displaying here is a javascript object. When referencing a "key" in this scenario, use theObject.theProperty as shown below

var node = {
  id: "jobs",
  label: "JES Jobs",
  nodeType: "ROOT",
  childNodesURI: "jobs?owner=*",
  childIds: [],
  isFetchingChildren: false,
  isToggled: true,
  jobName: ""
};

// Access the object property ID
console.log(node.id);

If you require a map, create it like this:

var myMap = new Map();

// Setting the values
myMap.set("id", "jobs");

console.log(myMap.get("id"));

If you wish to build a map based on your object, follow this approach

var node = {
  id: "jobs",
  label: "JES Jobs",
  nodeType: "ROOT",
  childNodesURI: "jobs?owner=*",
  childIds: [],
  isFetchingChildren: false,
  isToggled: true,
  jobName: ""
};

function constructMap(obj) {
    let map = new Map();
    Object.keys(obj).forEach(key => {
        map.set(key, obj[key]);
    });
    return map;
}

const map = constructMap(node);

console.log(map.get("id"));

Answer 2

What you're displaying here is a javascript object. When referencing a "key" in this scenario, use theObject.theProperty as shown below

var node = {
  id: "jobs",
  label: "JES Jobs",
  nodeType: "ROOT",
  childNodesURI: "jobs?owner=*",
  childIds: [],
  isFetchingChildren: false,
  isToggled: true,
  jobName: ""
};

// Access the object property ID
console.log(node.id);

If you require a map, create it like this:

var myMap = new Map();

// Setting the values
myMap.set("id", "jobs");

console.log(myMap.get("id"));

If you wish to build a map based on your object, follow this approach

var node = {
  id: "jobs",
  label: "JES Jobs",
  nodeType: "ROOT",
  childNodesURI: "jobs?owner=*",
  childIds: [],
  isFetchingChildren: false,
  isToggled: true,
  jobName: ""
};

function constructMap(obj) {
    let map = new Map();
    Object.keys(obj).forEach(key => {
        map.set(key, obj[key]);
    });
    return map;
}

const map = constructMap(node);

console.log(map.get("id"));

Answer 3

Answer №2

To retrieve the value of `node.id`, simply use the existing code you have. There is no built-in `get()` method for object literals unless you manually add it to the prototype.

According to the documentation, a `Map` should accept an iterable object as a parameter when creating one. However, in practical usage, passing an object instead of an array can result in an error stating `undefined is not a function`. Moreover, the browser support for this feature seems incomplete (https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Map).

As indicated in the reference:

[1] Chrome 31 onwards, this feature was available behind a preference setting. To enable it, go to chrome://flags and activate “Enable Experimental JavaScript”.

Your two options are: either iterate over your JSON object

var m = new Map();
var json = {'foo': 'bar'};

for (var i in json) {
    m.set(i, json[i]);
}
m.get('foo');

Alternatively, if you do not require the methods provided by `Map`, you can stick with the object literal approach.

json.foo;

Answer 4

To retrieve the value of `node.id`, simply use the existing code you have. There is no built-in `get()` method for object literals unless you manually add it to the prototype.

According to the documentation, a `Map` should accept an iterable object as a parameter when creating one. However, in practical usage, passing an object instead of an array can result in an error stating `undefined is not a function`. Moreover, the browser support for this feature seems incomplete (https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Map).

As indicated in the reference:

[1] Chrome 31 onwards, this feature was available behind a preference setting. To enable it, go to chrome://flags and activate “Enable Experimental JavaScript”.

Your two options are: either iterate over your JSON object

var m = new Map();
var json = {'foo': 'bar'};

for (var i in json) {
    m.set(i, json[i]);
}
m.get('foo');

Alternatively, if you do not require the methods provided by `Map`, you can stick with the object literal approach.

json.foo;

Why is it that I cannot use the .get method on JSON data? And what is the best way to convert JSON into a map?

Answer №1

Answer №2

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