Javascript - Accessing a specific element in an array using a variable

Question

Javascript - Accessing a specific element in an array using a variable

I am currently developing a webpage that interacts with a CGI backend. While the CGI backend is functioning well, my limited knowledge of JavaScript is making it hard for me to manage the results retrieved from AJAX JSON requests.

Here's what I have:

A JavaScript function sends queries to the CGI.

The CGI responds with a JSON array.

    {
    "ARRAY": [
        {
            "line": "1",
            "numbers": "12321",
            "var": "12321",
            "var2": "12321"
        },
        {
            "line": "2",
            "numbers": "-1",
            "var": "12320",
            "var2": "6160"
        }
    ]
}

The 'line', 'numbers', 'var', and 'var2' data must be displayed in separate cells of a table.

<table>
<tr>
<th>line</th><th>numbers</th><th>var</th><th>var2</th>
</tr>
<tr>
<td>ARRAY[0].line</td><td>ARRAY[0].numbers</td><td>ARRAY[0].var</td><td>ARRAY[0].var2</td>
</tr>
<tr>
<td>ARRAY[1].line</td><td>ARRAY[1].numbers</td><td>ARRAY[1].var</td><td>ARRAY[1].var2</td>
</tr>
</table>

My current issue is:

I don't know beforehand how many objects will be stored inside the array. In this example, there are 2, but there could be up to 20 or more. I am open to modifying my JSON structure if necessary. How can I create a loop that iterates through all the objects in the array?

javascript arrays json loops cgi

Answer 1

Answer №1

There are a few methods available for iterating through an array. One common way is to use a simple for loop like this:

for (var i = 0, len = ARRAY.length; i < len; i++) {
    //Build table row using ARRAY[i].line, etc
}

Another option is to use Array.forEach, which is supported in newer browsers and can be polyfilled for older versions as well:

ARRAY.forEach(function(idx, elt) {
    //Build table row using elt.line, etc
});

If you prefer using jQuery, there's also the $.each function:

$.each(ARRAY, function(idx, elt) {
    //Build table row using elt.line, etc
});

For a more detailed example utilizing the jQuery library, consider the following:

var url = '/cgi-bin/your_script_name.cgi';
var html = '<table><tr><th>line</th><th>numbers</th><th>var</th><th>var2</th></tr>';
$.get(url, function(response) {
    $.each(response.ARRAY, function(idx, elt) {
        html += '<tr><td>' + elt.line + '</td><td>' + elt.numbers + '</td><td>' + elt.var + '</td><td>' + elt.var2 + '</td></tr>';
    });
    html += '</table>';
    $('#target-element').html(html);
});

In this example, the generated table will be inserted into an element with the id target-element, and the cgi script URL is assumed to be located at /cgi-bin/your_script_name.cgi. If jQuery is not an option, you'll have to handle the AJAX request manually using XMLHttpRequest and parsing the response appropriately. I hope this explanation was helpful.

Answer 2

There are a few methods available for iterating through an array. One common way is to use a simple for loop like this:

for (var i = 0, len = ARRAY.length; i < len; i++) {
    //Build table row using ARRAY[i].line, etc
}

Another option is to use Array.forEach, which is supported in newer browsers and can be polyfilled for older versions as well:

ARRAY.forEach(function(idx, elt) {
    //Build table row using elt.line, etc
});

If you prefer using jQuery, there's also the $.each function:

$.each(ARRAY, function(idx, elt) {
    //Build table row using elt.line, etc
});

For a more detailed example utilizing the jQuery library, consider the following:

var url = '/cgi-bin/your_script_name.cgi';
var html = '<table><tr><th>line</th><th>numbers</th><th>var</th><th>var2</th></tr>';
$.get(url, function(response) {
    $.each(response.ARRAY, function(idx, elt) {
        html += '<tr><td>' + elt.line + '</td><td>' + elt.numbers + '</td><td>' + elt.var + '</td><td>' + elt.var2 + '</td></tr>';
    });
    html += '</table>';
    $('#target-element').html(html);
});

In this example, the generated table will be inserted into an element with the id target-element, and the cgi script URL is assumed to be located at /cgi-bin/your_script_name.cgi. If jQuery is not an option, you'll have to handle the AJAX request manually using XMLHttpRequest and parsing the response appropriately. I hope this explanation was helpful.

Javascript - Accessing a specific element in an array using a variable

Answer №1

Similar questions

Leveraging a global array in a PHP multi-page form

Master the Art of Scrollbar Control in Angular!

Forming a distinct array from a collection of objects

Decoding JSON Data in Google Web Toolkit

Guide on exporting a reducer from a Node module built on React Redux

Passing the reference of every row in a matrix to a function

Creating a dynamic Bootstrap 5 carousel with active class on the first item and indicators

Trouble with highlighting the chosen menu item

Combining data from an element in a list with a state object in Redux

The issue with AngularJS array filtering remains unresolved

Convert HTML table to CSV format while retaining merged rows and columns

Extract the complete HTML information from the weather website

Any tips or hacks for successfully implementing vw resizing on the :before pseudo-element in webkit browsers?

Can you explain the return value of array.find() in Typescript or Java script?

Tips for toggling a menu by clicking a link

What is preventing me from accessing arguments.callee within this function in sloppy mode?

What is the best way to release a collection of string pointers in C++?

How to Create Smooth Transitions for Text Arrays using jQuery's Fade In and Fade Out Features

What is the best way to retrieve all records from a MongoDB collection?

Modify the input field in the datepicker to resemble a button