Develop Reference

How could I make this JSON data usable on an API?

JSON data currently looks like this string:
["ID","Name","Age"],["212","David","38"]
And I would like for it to look like this:
{"ID":"212","Name":"David","Age":"38"}
Thanks for your help in advance
I found this code and it solves most of the issue
var columns = ["ID", "Name", "Age"];
var rows = ["212", "David", "38"];
var result = rows.reduce(function(result, field, index) {
result[columns[index]] = field;
return result;
}, {})
console.log(result);

You could do that with following steps:
extract keys and values from array
zip them to key match value
use Object.fromEntries to create object key-value
let obj = [["ID","Name","Age"],["212","David","38"]]
let [keys, values] = obj;
let zipped = keys.map((key, i)=>[key, values[i]]);
let output = Object.fromEntries(zipped);
console.log(output);

lets say
let jsonVal = [["ID","Name","Age"],["212","David","38"], ["212","David","38"]]
0th index will have the keys and remaining is data
let newJsonVal = [] ​
for (let i =1; i< jsonVal.length-1; i++) {
​let newObject ={}
​jsonVal[i].map((d,j) => {
​newObject[jsonVal[0][j] = d;
​})
newJsonVal.push(newObject)
}
newJsonVal will have array of object as you need

save and display an array of JSON/JS object(name/value pair) value as a comma separated string

var obj = {
aray1:[1,2],
aray2:["a","b"],
aray3:["ab","abab"]
};
this is the object i have values and i want to store the above array values as as a comma separated string and display as comma separated string on UI.
DB used is Mongo.

I think you are looking for a join method on arrays.
What you can do is obj.aray1.join(",") which will return 1,2 that you can display in your UI

As #eddyP23 mentioned, [].join will do the job for you.
var obj = {
aray1:[1,2],
aray2:["a","b"],
aray3:["ab","abab"]
};
var result = "";
for(key in obj){
result += ","+obj[key].join(",")
}
console.log(result.substring(1));

var obj = {
aray1:[1,2],
aray2:["a","b"],
aray3:["ab","abab"]
};
var a = Object.keys(obj).map(function(key){
return obj[key]
})
console.log(a.toString())

Convert string into array of object in javascript

Need to convert string into array of object in JavaScript. Here is the example,
var str = "1,2";
output:
"values":[
{"id":"1"},
{"id":"2"}
];

Make use of map():
var str = "1,2";
var s = str.split(',').map(function(x){
return {"id" : x};
})
str = {"values" : s};
console.log(JSON.stringify(str));

try this:
var str = "1,2";
str = str.split(",");
var obj = {'value':[]};
str.forEach(function(val){
obj.value.push({'id':val})
});

str = "1,2"
var res = str.split(",");
values = []
for each (var item in res ) {
values .push({
id: item
});
}
console.log(JSON.stringify(values));
use split , list push and loop

Use map. Both split (for converting the string to an array) and map (which returns a new array for each element of the array that is passed through the provided function) are chainable so you can do the following:
var values = str.split(',').map(function (el) {
return { id: el };
});
DEMO
It's not clear whether you want just an array of objects, or a JSON string of that array. If it's the latter, use JSON.stringify(result).

How to convert a array containing object string to regular key object pair?

I am trying to convert my uri to object value, as a success level i converted and splited in to array values with colon. But i am not able to onvert those to regular object. any one suggest me a good way. I am suing underscorejs with me.
here is my code :
var ar = ["id:1231", "currency:GBP"];
var outPut = _.map(ar, function(item){
return '{' + item + '}';
})
console.log(outPut); //consoles as ["{id:1231}", "{currency:GBP}"]
how can i get result like this:
var object = {id:1231, currency:GBP}
is underscore has any in build method for this?

There are several ways you could go about this, and Underscore offers helpers for them.
One way would be to use _.reduce to incrementally add key/value pairs to an initially empty "result" object:
var obj = _.reduce(ar, function(result, item) {
var keyAndValue = item.split(":");
result[keyAndValue[0]] = keyAndValue[1];
return result;
}, {});
Note that you can do the same without Underscore unless you have to support IE 8 or earlier.

Without any third part library:
var output = {} ;
var ar = ["id:1231", "currency:GBP"];
ar.forEach(function (item) {
var values = item.split(':') ;
output[values[0]] = values[1] ;
}) ;
Output console.log(output):
Object {id: "1231", currency: "GBP"}

Here is another version using jQuery:
var newObj = {};
$.each( ar, function( i, v ) {
var kv = v.split( ":" );
newObj[ kv[0] ] = kv[ 1 ];
});
// newObj = {id:"1231", currency:"GBP"}

Declaring array of objects

I have a variable which is an array and I want every element of the array to act as an object by default. To achieve this, I can do something like this in my code.
var sample = new Array();
sample[0] = new Object();
sample[1] = new Object();
This works fine, but I don't want to mention any index number. I want all elements of my array to be an object. How do I declare or initialize it?
var sample = new Array();
sample[] = new Object();
I tried the above code but it doesn't work. How do I initialize an array of objects without using an index number?

Use array.push() to add an item to the end of the array.
var sample = new Array();
sample.push(new Object());
To do this n times use a for loop.
var n = 100;
var sample = new Array();
for (var i = 0; i < n; i++)
sample.push(new Object());
Note that you can also substitute new Array() with [] and new Object() with {} so it becomes:
var n = 100;
var sample = [];
for (var i = 0; i < n; i++)
sample.push({});

Depending on what you mean by declaring, you can try using object literals in an array literal:
var sample = [{}, {}, {} /*, ... */];
EDIT: If your goal is an array whose undefined items are empty object literals by default, you can write a small utility function:
function getDefaultObjectAt(array, index)
{
return array[index] = array[index] || {};
}
Then use it like this:
var sample = [];
var obj = getDefaultObjectAt(sample, 0); // {} returned and stored at index 0.
Or even:
getDefaultObjectAt(sample, 1).prop = "val"; // { prop: "val" } stored at index 1.
Of course, direct assignment to the return value of getDefaultObjectAt() will not work, so you cannot write:
getDefaultObjectAt(sample, 2) = { prop: "val" };

You can use fill().
let arr = new Array(5).fill('lol');
let arr2 = new Array(5).fill({ test: 'a' });
// or if you want different objects
let arr3 = new Array(5).fill().map((_, i) => ({ id: i }));
Will create an array of 5 items. Then you can use forEach for example.
arr.forEach(str => console.log(str));
Note that when doing new Array(5) it's just an object with length 5 and the array is empty. When you use fill() you fill each individual spot with whatever you want.

After seeing how you responded in the comments. It seems like it would be best to use push as others have suggested. This way you don't need to know the indices, but you can still add to the array.
var arr = [];
function funcInJsFile() {
// Do Stuff
var obj = {x: 54, y: 10};
arr.push(obj);
}
In this case, every time you use that function, it will push a new object into the array.

You don't really need to create blank Objects ever. You can't do anything with them. Just add your working objects to the sample as needed. Use push as Daniel Imms suggested, and use literals as Frédéric Hamidi suggested. You seem to want to program Javascript like C.
var samples = []; /* If you have no data to put in yet. */
/* Later, probably in a callback method with computed data */
/* replacing the constants. */
samples.push(new Sample(1, 2, 3)); /* Assuming Sample is an object. */
/* or */
samples.push({id: 23, chemical: "NO2", ppm: 1.4}); /* Object literal. */
I believe using new Array(10) creates an array with 10 undefined elements.

You can instantiate an array of "object type" in one line like this (just replace new Object() with your object):
var elements = 1000;
var MyArray = Array.apply(null, Array(elements)).map(function () { return new Object(); });

Well array.length should do the trick or not? something like, i mean you don't need to know the index range if you just read it..
var arrayContainingObjects = [];
for (var i = 0; i < arrayContainingYourItems.length; i++){
arrayContainingObjects.push {(property: arrayContainingYourItems[i])};
}
Maybe i didn't understand your Question correctly, but you should be able to get the length of your Array this way and transforming them into objects. Daniel kind of gave the same answer to be honest. You could just save your array-length in to his variable and it would be done.
IF and this should not happen in my opinion you can't get your Array-length. As you said w/o getting the index number you could do it like this:
var arrayContainingObjects = [];
for (;;){
try{
arrayContainingObjects.push {(property: arrayContainingYourItems[i])};
}
}
catch(err){
break;
}
It is the not-nice version of the one above but the loop would execute until you "run" out of the index range.

//making array of book object
var books = [];
var new_book = {id: "book1", name: "twilight", category: "Movies", price: 10};
books.push(new_book);
new_book = {id: "book2", name: "The_call", category: "Movies", price: 17};
books.push(new_book);
console.log(books[0].id);
console.log(books[0].name);
console.log(books[0].category);
console.log(books[0].price);
// also we have array of albums
var albums = []
var new_album = {id: "album1", name: "Ahla w Ahla", category: "Music", price: 15};
albums.push(new_album);
new_album = {id: "album2", name: "El-leila", category: "Music", price: 29};
albums.push(new_album);
//Now, content [0] contains all books & content[1] contains all albums
var content = [];
content.push(books);
content.push(albums);
var my_books = content[0];
var my_albums = content[1];
console.log(my_books[0].name);
console.log(my_books[1].name);
console.log(my_albums[0].name);
console.log(my_albums[1].name);
This Example Works with me.
Snapshot for the Output on Browser Console

Try this-
var arr = [];
arr.push({});

const sample = [];
list.forEach(element => {
const item = {} as { name: string, description: string };
item.name= element.name;
item.description= element.description;
sample.push(item);
});
return sample;
Anyone try this.. and suggest something.

Use array.push() to add an item to the end of the array.
var sample = new Array();
sample.push(new Object());
you can use it
var x = 100;
var sample = [];
for(let i=0; i<x ;i++){
sample.push({})
OR
sample.push(new Object())
}

Using forEach we can store data in case we have already data we want to do some business login on data.
var sample = new Array();
var x = 10;
var sample = [1,2,3,4,5,6,7,8,9];
var data = [];
sample.forEach(function(item){
data.push(item);
})
document.write(data);
Example by using simple for loop
var data = [];
for(var i = 0 ; i < 10 ; i++){
data.push(i);
}
document.write(data);

If you want all elements inside an array to be objects, you can use of JavaScript Proxy to apply a validation on objects before you insert them in an array. It's quite simple,
const arr = new Proxy(new Array(), {
set(target, key, value) {
if ((value !== null && typeof value === 'object') || key === 'length') {
return Reflect.set(...arguments);
} else {
throw new Error('Only objects are allowed');
}
}
});
Now if you try to do something like this:
arr[0] = 'Hello World'; // Error
It will throw an error. However if you insert an object, it will be allowed:
arr[0] = {}; // Allowed
For more details on Proxies please refer to this link:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
If you are looking for a polyfill implementation you can checkout this link:
https://github.com/GoogleChrome/proxy-polyfill

The below code from my project maybe it good for you
reCalculateDetailSummary(updateMode: boolean) {
var summaryList: any = [];
var list: any;
if (updateMode) { list = this.state.pageParams.data.chargeDefinitionList }
else {
list = this.state.chargeDefinitionList;
}
list.forEach((item: any) => {
if (summaryList == null || summaryList.length == 0) {
var obj = {
chargeClassification: item.classfication,
totalChargeAmount: item.chargeAmount
};
summaryList.push(obj);
} else {
if (summaryList.find((x: any) => x.chargeClassification == item.classfication)) {
summaryList.find((x: any) => x.chargeClassification == item.classfication)
.totalChargeAmount += item.chargeAmount;
}
}
});
if (summaryList != null && summaryList.length != 0) {
summaryList.push({
chargeClassification: 'Total',
totalChargeAmount: summaryList.reduce((a: any, b: any) => a + b).totalChargeAmount
})
}
this.setState({ detailSummaryList: summaryList });
}

var ArrayofObjects = [{}]; //An empty array of objects.