Working with array of objects in JavaScript

Question

Question: Develop an array of 1000 objects (having properties name and number as shown).

We need a function to convert every object so the name is uppercased and values are 5 times the original and store into the higher variable. Similarly, another function that converts every object so the name is lower case and value is 3 times the original, store this into the little variable.
We need a function that takes each object in higher and finds all objects in little that evenly divide into it. Example: 30 in higher object is evenly divided by 6 in little.
The output of 2 must be an array of higher numbers, and in every object there should be got (which is a variable inside the object) which will contain every little object that evenly divided the higher.

My code:

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body>

<script>
    var n = 1000;
var sample = [];
for (var i = 0; i < n; i++) sample.push({
   name:'John' + i,
   value: i 
});
console.log(sample);

function Converter() {
    var n = 1000;
    var higher = sample;
    for (var i = 0; i < n; i++) higher.name = 'John' + i;
    higher.value = i * 5;
    console.log(higher);
}
    </script>

</body>
</html>

The array of objects is created and it is as expected/required by the question, however, the converter function for higher does not work, also how should the 3rd question be done?

sample is the array, not an item inside the array. When you access higher.name and higher.value you are accessing an undefined property in the array. Also, your syntax is not correct, for has missing braces and you probably didn't intend to do that. — E. Zacarias
– E. Zacarias, Commented Oct 2, 2018 at 20:38

Jonas Wilms · Accepted Answer · 2018-10-02 21:01:16Z

2

Some thoughts:

1) only constructors should start with a capital letter, functions should be camelcase by convention so it should be converter

2) you don't call converter() so it never gets executed

3) make sure to indent your code properly var n and var sample should be at the same depth.

4) if you omit the brackets after an if or for, only the following statement gets inside the branch, so in your case you do:

 for (var i = 0; i < n; i++)
     higher.name = 'John'+i;
 higher.value = i*5;

so the second line isn't even executed in the loop, you want:

for (var i = 0; i < n; i++) {
    higher.name = 'John'+i;
    higher.value = i*5;
}

5) higher.name makes little sense as higher is an array, you want to change the name of the ith higher number which you can do with higher[i].name

6) "John1" is not in caps, you want to call toUpperCase on it (("John1").toUpperCase())

also how should the 3rd question be done?

I guess fixing your code and doing the second question is enough for today.

You could continue reading:

Coding style matters

js array iterations

edited Oct 2, 2018 at 21:01

answered Oct 2, 2018 at 20:39

Jonas Wilms

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4 Comments

John McDonald Over a year ago

How should I proceed with the 2nd question? I think I have to compare 2 arrays. This is one of the main questions that I'm stuck at.

Jonas Wilms Over a year ago

@john first fix your code!! make yourself familiar with the console and the tools, get some more basics. You haven't even found the most basic errors in your code, you cannot write more conplex code without failing completely. Do it step by step.

slider Over a year ago

Is it appropriate to suggest Array.prototype.map or will that be too much?

Jonas Wilms Over a year ago

@slider if you look at john's question history, one can clearly see that he is dumping is homework here, full of typos & syntax errors and the community produces clean and copy+paste ready answers ... The array methods are definetly good to point out but I would not give any code.

slider · Accepted Answer · 2018-10-02 21:07:57Z

1

You should also try to think in a more structured manner about your code here. I would suggest writing separate functions for each problem and giving them meaningful names. Perhaps something like the following:

var n = 1000;
var sample = [];
for (var i = 0; i < n; i++) sample.push({
    name: 'John' + i,
    value: i
});
console.log(sample);

var higher = convertToHigher(sample);
var little = convertToLittle(sample);
var higherWithDivisors = findAllDivisors(higher, little);

function convertToHigher(arr) {
    var newArr = [];
    // TODO: iterate through each entry in arr, create a new modified object 
    // with a higher value and add it to newArr
    return newArr;
}

function convertToLittle(arr) {
    var newArr = [];
    // TODO: iterate through each entry in arr, create a new modified object
    // with a lower value and add it to newArr
    return newArr;
}

function findAllDivisors(arr1, arr2) {
    var newArr = [];
    // TODO: solve problem 3 here
    return newArr;
}

answered Oct 2, 2018 at 21:07

slider

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1 Comment

John McDonald Over a year ago

Thank-you @slider. I tried to develop convertToHigher, however, it does not work. The code

function convertToHigher(arr){         var newArr = [];         var n = 1000;         for (var i = 0; i < n; i++){         arr[i].name = 'JOHN' + i;         arr.value = i * 5;          }            console.log(arr);         return newArray;     }

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