JavaScript Output

JavaScript can display data in different ways using:

console.log() Object
alert() Object
document.write() Object
elem.innerHTML Property - elem is an arbitrary name.

console.log()

As shown in the previous article, you can debug unexpected results from the browser in the console.

index.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Using log Object</title>
</head>

<body>

    <script>
        console.log('Hello World!')
    </script>
</body>

</html>

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alert method

The alert is a method on the browser window object - window.alert(...). It is used to display data on the browser or screen (window). It displays the result in a modal dialog box.

index.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=, initial-scale=1.0">
    <title>Using alert object</title>
</head>

<body>

    <script>
        alert('Hello World!')
    </script>
</body>

</html>

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write method

To test for unexpected results directly in the browser window, the command document.write() is used. It allows HTML elements within the method. For example document.write("<h1>Hello World</h1>").

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=, initial-scale=1.0" />
    <title>Using write object</title>
  </head>

  <body>
    <script>
      document.write("<h2>Hello World!</h2>");
    </script>
  </body>
</html>

Edit on Stackblitz

innerHTML property

The innerHTML property is used on selected elements to target specific elements based on their selector to allow HTML content within the element.

index.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=, initial-scale=1.0" />
    <title>Using innerHTML</title>
</head>

<body>
   <h2 id="demo"></h2>
    <script>
       let elem = document.querySelector("#demo");
           elem.innerHTML = "Hello World!";
    </script>
</body>

</html>

Edit on Stackblitz

Outside of the console, but in the window browser, you use the alert method on the window object or document property — window.alert('...'), window.document.write('...'), window.document.querySelector('#demo') = "...".

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