Calling an ASP.NET Core API

Calling an ASP.NET Core API: free step-by-step lesson with examples, common mistakes, and interview tips — part of jQuery Tutorial on Toolliyo Academy.

8 min read Updated 8/24/2026

On this page

jQuery Tutorial · Lesson 50 of 100

Calling an ASP.NET Core API

Setup & DOM ✓ → Events Effects AJAX → Perf & Integrate → Ship & Projects

Events Effects AJAX · 2 — Interact · ~6 min · AJAX and APIs

What is this?

Call your own API with relative URLs, JSON contentType, and credentials/cookies as configured. Map C# DTOs to jQuery payloads carefully (camelCase vs PascalCase).

Why should you care?

QueryVerse in real shops sits on ASP.NET Core — demos against jsonplaceholder teach the shape; production uses /api/...

See it live — copy this example

Examples include the jQuery 3.7 CDN. Paste into an HTML file or use Run Example to preview.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>QueryVerse</title>
  <style>
    body { font-family: system-ui, sans-serif; margin: 1.25rem; }
    .box { padding: .75rem; border: 1px solid #ccc; border-radius: 8px; margin: .5rem 0; }
    .muted { color: #666; }
    button { margin-right: .35rem; margin-top: .35rem; }
    input, select, textarea { margin: .25rem 0; }
    table { border-collapse: collapse; width: 100%; }
    th, td { border: 1px solid #ddd; padding: .4rem .55rem; text-align: left; }
    .hidden { display: none; }
    .row-odd { background: #f7f7f7; }
    .active { font-weight: 700; }
    .toast { background: #111; color: #fff; padding: .5rem .75rem; border-radius: 6px; }
  </style>
</head>
<body>
  <button type="button" id="mock">Mock Core-style call</button>
  <pre id="out" class="box muted"></pre>
<script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
<script>
$(function () {
  $('#mock').on('click', function () {
    var payload = { employeeCode: 'E7781', city: 'Pune' };
    // Training pattern — swap url to '/api/employees' on a real host
    $.ajax({
      method: 'POST',
      url: 'https://jsonplaceholder.typicode.com/posts',
      contentType: 'application/json; charset=utf-8',
      dataType: 'json',
      data: JSON.stringify(payload)
    })
      .done(function (res) {
        $('#out').text('Posted JSON body echoed id=' + res.id + '\n' + JSON.stringify(payload, null, 2));
      })
      .fail(function (xhr) {
        $('#out').text('API error ' + xhr.status);
      });
  });
});
</script>
</body>
</html>

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>QueryVerse</title>
  <style>
    body { font-family: system-ui, sans-serif; margin: 1.25rem; }
    .box { padding: .75rem; border: 1px solid #ccc; border-radius: 8px; margin: .5rem 0; }
    .muted { color: #666; }
    button { margin-right: .35rem; margin-top: .35rem; }
    input, select, textarea { margin: .25rem 0; }
    table { border-collapse: collapse; width: 100%; }
    th, td { border: 1px solid #ddd; padding: .4rem .55rem; text-align: left; }
    .hidden { display: none; }
    .row-odd { background: #f7f7f7; }
    .active { font-weight: 700; }
    .toast { background: #111; color: #fff; padding: .5rem .75rem; border-radius: 6px; }
  </style>
</head>
<body>
  <button type="button" id="mock">Mock Core-style call</button>
  <pre id="out" class="box muted"></pre>
<script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
<script>
$(function () {
  $('#mock').on('click', function () {
    var payload = { employeeCode: 'E7781', city: 'Pune' };
    // Training pattern — swap url to '/api/employees' on a real host
    $.ajax({
      method: 'POST',
      url: 'https://jsonplaceholder.typicode.com/posts',
      contentType: 'application/json; charset=utf-8',
      dataType: 'json',
      data: JSON.stringify(payload)
    })
      .done(function (res) {
        $('#out').text('Posted JSON body echoed id=' + res.id + '\n' + JSON.stringify(payload, null, 2));
      })
      .fail(function (xhr) {
        $('#out').text('API error ' + xhr.status);
      });
  });
});
</script>
</body>
</html>

Result