Develop Reference

Array element comparison with Json response in Javascript

I have a Json response which looks like this.
[
{
"name": "name1",
"id": "1"
},
{
"name": "name2",
"id": "2"
},
{
"name": "name4",
"id": "4"
},
{
"name": "name5",
"id": "5"
}
]
I have another array called "a" which has only id [1,2,3,4,5]. Now i have to compare every element in the array with json response object id. For example, the first element of array "a" exists in json response object , then its respective name should be retrieved and stored in another new array called "b" -> [name1]. The second element of array "a" exists in json response object , then its respective name should be retrieved and appended in "b" array -> [name1,name2]. The third element of array "a" does not exists in json response object , hence no name. In this case, Instead of name, "0" should be appedned in b array for that id -> [name1,name2,0]. The fourth element of array "a" exists in json response object , then its respective name should be retrieved and appended in b array -> [name1,name2,0,name4]. The fifth element of array "a" exists in json response object , then its respective name should be retrieved and appended in b array -> [name1,name2,0,name4,name5].
I tried to implement this by the following code. But instead of [name1,name2,0,name4,name5] , I am getting [name1,name2,name4,name5,0]
for (var i = 0; i < a.length; i++) {
if (a.includes(jsonResponse[i].id)) {
b.push(jsonResponse[i].name);
}
else{
b.push("0");
}
}

You need to search for each element of b in the entire jsonResponse array, not just test the current index of jsonResponse.
Use .find() to find the element with the ID you're looking for.
let jsonResponse = [{
"name": "name1",
"id": "1"
},
{
"name": "name2",
"id": "2"
},
{
"name": "name4",
"id": "4"
},
{
"name": "name5",
"id": "5"
}
];
let a = [1, 2, 3, 4, 5];
let b = a.map(id => {
let found = jsonResponse.find(u => u.id == id);
return found ? found.name : "0";
});
console.log(b);

You can use Map collection to have O(1) while accessing to the desired element when you map your elements:
let mapResponse = new Map(jsonResponse.map(s=> [+s.id, s.name]));
const result = a.map(id => mapResponse.get(id) || '0')
An example:
let jsonResponse = [
{
"name": "name1",
"id": "1"
},
{
"name": "name2",
"id": "2"
},
{
"name": "name4",
"id": "4"
},
{
"name": "name5",
"id": "5"
}
];
let a = [1, 2, 3, 4, 5];
let mapResponse = new Map(jsonResponse.map(s=> [+s.id, s.name]));
const result = a.map(id => mapResponse.get(id) || '0')
console.log(result);

Convert array of objects into lowercase

Array looks like this:
"myTags":
[{
"type":"one",
"value":"Testing",
"note":"Hey"
},{
"type":"two",
"value":"Yg5GE",
"note":"hey2"
}]
I need to convert type:'one' value 'Testing' into lowercase i.e. value = Testing needs to be 'testing'. Is there a way to so this keeping the same structure?
Note: "type":"one","value":"Testing", may not always be included in the array. So I guess in this scenario I first need to do a check if they exist?
I have tried .map, however I am unable to get the result I want. Any help would be appreciated.
Ideal structure:
"myTags":
[{
"type":"one",
"value":"testing",
"note":"hey"
},{
"type":"two",
"value":"Yg5GE",
"note":"hey2"
}]

Iterate over the elements in myTags, check if type is "one" and only then change the content of value to lowercase (if present)
var data = {
"myTags": [{
"type": "one",
"value": "Testing",
"note": "Hey"
}, {
"type": "one",
"note": "Hey"
}, {
"type": "two",
"value": "Yg5GE",
"note": "hey2"
}]
};
data.myTags.forEach(function(tag) {
if (tag.type === "one" && typeof tag.value !== "undefined") {
tag.value = tag.value.toLowerCase();
}
});
console.log(data.myTags);
You may also first filter the content of myTags to get the element(s) with "type": "one" and only iterate over those element(s)
var data = {
"myTags": [{
"type": "one",
"value": "Testing",
"note": "Hey"
}, {
"type": "one",
"note": "Hey"
}, {
"type": "two",
"value": "Yg5GE",
"note": "hey2"
}]
};
data.myTags
.filter(function(tag) {
return tag.type === "one";
})
.forEach(function(tag) {
if (typeof tag.value !== "undefined") {
tag.value = tag.value.toLowerCase();
}
});
console.log(data.myTags);

This one works perfectly
$(document).ready(function(){
var objects ={"myTags":
[{"type":"one","value":"Testing", "note":"Hey"}
,{ "type":"two", "value":"Yg5GE", "note":"hey2"}]};
var obj = objects.myTags.map(function(a) {
a.value = a.value.toLowerCase();
return a;
});
console.log(obj);
});
output:
{type: "one", value: "testing", note: "Hey"}
{type: "two", value: "yg5ge", note: "hey2"}
Thank you

Achieve this very simply by using an arrow function and the map() method of the Array
var words = ['Foo','Bar','Fizz','Buzz'].map(v => v.toLowerCase());
console.log(words);

convert integer to array of object.

var items = [
{ "id": 1, "label": "Item1" },
{ "id": 2, "label": "Item2" },
{ "id": 3, "label": "Item3" }
];
I have this array of objects named 'items'. I get itemselected = 3 from the database.
I need to convert this 3 into the following form.
0:Object
id:3
label:"Item3"
Similarly, if i have a value 2 coming from the database, i should convert it to
0:Object
id:2
label:"Item2"
Can anyone please let me hint of how to get it solved. i am not here to get the answer. These questions are quite tricky for me and i always fail to get the logic right. Any advice on how to master this conversions will be of great help. thanks.

Since you tagged underscore.js, this should be very easy:
var selectedObject = _.findWhere(items, {id: itemselected});
Using ECMA6, you can achieve the same using .find method on arrays:
let selectedObject = items.find(el => el.id === itemselected);
With ECMA5, you can use filter method of arrays. Be careful that filter returns undefined if no element has been found:
var selectedObject = items.filter(function(el) { return el.id === itemselected});

Use jquery $.map function as below
$.map(item, function( n, i ) { if(n["id"] == 3) return ( n );});

Based on the title of your question: «convert integer to array of object». You can use JavaScript Array#filter.
The filter() method creates a new array with all elements that
pass the test implemented by the provided function.
Something like this:
var items = [{
"id": 1,
"label": "Item1"
},
{
"id": 2,
"label": "Item2"
},
{
"id": 3,
"label": "Item3"
}
];
var value = 2;
var result = items.filter(function(x) {
return x.id === value;
});
console.log(result); // Prints an Array of object.

Try this
var obj = {} ;
items = [
{ "id": 1, "label": "Item1" },
{ "id": 2, "label": "Item2" },
{ "id": 3, "label": "Item3" }
];
items.map(function(n) { obj[n.id] = n });

Access nested members in JSON

I'm trying to access members in a json, however I am running into some trouble. Here is an example of one of the json objects, stored in var obj:
var fs = require('fs');
var obj = [
{
"_id": "52d7f816f96d7f6f31fbb680",
"regNum": "0361300035313000002",
"sd": "2013-01-01T00:00:00",
"pd": "2013-01-25T09:30:29Z",
"prd": "2012-12-18",
"p": 1395000000,
"pt": [
{
"name": name here",
"price": 1395000000,
"OKDP": {
"code": "5520109",
"name": "name here"
},
"sid": "25484812",
"sum": "1395000000",
"OKEI": {
"code": "796",
"name": "name two"
},
"quantity": "1"
}
],
"b": 0,
"c": 0,
"s": 0
}
];
I'm trying to access the sid and sum values, by doing the following:
var sid = [];
var sum = [];
obj.forEach(block => {
var sidOut = block.pt.sid;
var sumOut = block.pt.sum;
sid.push(sidOut);
sum.push(sumOut);
});
console.log(sid);
console.log(sum);
I tried the solution here, however, when I run these it gives me [ undefined ] errors.
Why am I unable to access this two values?

if you see your pt is an array of an object [{}] so you need to select which element you want to access so
var sidOut = block.pt[0].sid;
var sumOut = block.pt[0].sum;
should get you the right result

Is this valid json data?

The url has following json data:
[{ "topic": "cricket",
"value": "Player [ playerid=123, category=b, high=150, total=2300]",
"place": "xyz"},
{ "topic": "cricket",
"value": "Player [ playerid=456, category=c, high=60, total=300]",
"place": "abc"},
{ "topic": "cricket",
"value": "Player [ playerid=789, category=a, high=178, total=5300]",
"place": "bnm"}]
I tried online to check whether this is valid json or not through following link: http://jsonformatter.curiousconcept.com/ it says valid. if it is, how do I access each playerid ?

It is valid JSON, but the data about the player is embedded in a random string. You can do one of two things:
Update the service to send back a different, valid JS value, for example:
"value": {
"type": "Player",
"playerid": 123,
"category": "b",
"high": 150,
"total": 2300
}
Parse the data in the value key yourself:
// Simple regex, not really "parsing"
var playerIdRE = /playerid=(\d+)/i;
var result = playerIdRE.exec(yourData[0].value);
// result[0] is the full match, while result[1] is the ID.
// Or the more complicated version that does full parsing
var format = /\s*(.*?)\s*\[\s*([^\]]+)\s*\]\s*/gi,
keyValuePair = /(\w+)=([^,\]]*),?\s*/gi
function parseComplexDataType(input) {
var result = format.exec(input),
typeName = result[1],
keyValues = result[2],
returnValue = {};
if (!typeName) return returnValue;
returnValue.typeName = typeName;
input.replace(keyValuePair, function(_, key, value) {
returnValue[key] = value;
});
return returnValue;
}
// Usage:
> parseComplexDataType("Player [ playerid=123, category=b, high=150, total=2300]")
Object {typeName: "Player", playerid: "123", category: "b", high: "150", total: "2300"}

For your purposes, it is not valid. Once the JSON is corrected, you simply need to loop through the array and read each value.
var jArray = [{
"topic": "cricket",
"value": {
"type": "Player",
"playerid": 123,
"category": "b",
"high": 150,
"total": 2300
},
"place": "xyz"
}, {
...
}]
To access the JSON data ...
for (var i=0,len=jArray.length; i<len; i++) {
console.log(jArray[i].topic, jArray[i].value.type);
}

Yes, it is. I check it via: http://jsonlint.com/
Extracting "playerid":
Initialise the string to JSONArray.
Iterate over each element in the above array.
Now, from each element extract "value".
Finally, from this string you can get "playerid" by using string methods (see the code below).
Below is the code in Java:
ArrayList<String> player_ids = new ArrayList<String>();
String s = "YOUR STRING";
JSONArray ja = new JSONArray(s);
for(int i =0; i<ja.length(); i++)
{
String value = ja.getJSONObject(i).getString("value");
int start = value.indexOf("=");
int end = value.indexOf(",");
String player_id = value.substring(start+1, end);
player_ids.add(player_id);
}
Hope it helps!!