Understanding the Keydown Event Listener in JavaScript: A Comprehensive Guide
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The "keydown" event in JavaScript is triggered when a key is pressed down on the keyboard. You can use an event listener to execute a function when the "keydown" event occurs on an element.
Here is an example of using an event listener to execute a function when a key is pressed down on the keyboard:
<span class="pln"> </span><span class="tag"><input</span><span class="pln"> </span><span class="atn">type</span><span class="pun">=</span><span class="atv">"text"</span><span class="pln"> </span><span class="atn">id</span><span class="pun">=</span><span class="atv">"myInput"</span><span class="tag">></span><span class="pln"> </span><span class="tag"><script></span><span class="pln"> </span><span class="com">// Define the function to be executed when a key is pressed down on the keyboard</span><span class="pln"> </span><span class="kwd">function</span><span class="pln"> keyPressed</span><span class="pun">(</span><span class="pln">event</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> console</span><span class="pun">.</span><span class="pln">log</span><span class="pun">(</span><span class="str">"Key was pressed down: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> event</span><span class="pun">.</span><span class="pln">key</span><span class="pun">);</span><span class="pln"> </span><span class="pun">}</span><span class="pln"> </span><span class="com">// Attach the function as an event listener to the "keydown" event on the input field</span><span class="pln"> document</span><span class="pun">.</span><span class="pln">getElementById</span><span class="pun">(</span><span class="str">"myInput"</span><span class="pun">).</span><span class="pln">addEventListener</span><span class="pun">(</span><span class="str">"keydown"</span><span class="pun">,</span><span class="pln"> keyPressed</span><span class="pun">);</span><span class="pln"> </span><span class="tag"></script></span><span class="pln"> </span>
In this example, the function keyPressed is defined and is attached as an event listener to the "keydown" event on the input field with the ID "myInput". When a key is pressed down on the keyboard, the function will be executed and the key that was pressed will be logged to the console.
Event listeners are a powerful tool for creating interactive and dynamic webpages. They can be attached to a wide range of events on different elements, such as mouse clicks, keyboard input, form submissions, and more.
Copy and paste below code and try it
<span class="pln"> </span><span class="dec"><!DOCTYPE html></span><span class="pln"> </span><span class="tag"><html></span><span class="pln"> </span><span class="tag"><body></span><span class="pln"> </span><span class="tag"><h2></span><span class="pln">Example of keydown event Listener in javascript</span><span class="tag"></h2></span><span class="pln"> </span><span class="tag"><input</span><span class="pln"> </span><span class="atn">type</span><span class="pun">=</span><span class="atv">"text"</span><span class="pln"> </span><span class="atn">id</span><span class="pun">=</span><span class="atv">"myInput"</span><span class="tag">></span><span class="pln"> </span><span class="tag"></body></span><span class="pln"> </span><span class="tag"></html></span><span class="pln"> </span><span class="tag"><script></span><span class="pln"> </span><span class="com">// Define the function to be executed when a key is pressed down on the keyboard</span><span class="pln"> </span><span class="kwd">function</span><span class="pln"> keyPressed</span><span class="pun">(</span><span class="pln">event</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> console</span><span class="pun">.</span><span class="pln">log</span><span class="pun">(</span><span class="str">"Key was pressed down: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> event</span><span class="pun">.</span><span class="pln">key</span><span class="pun">);</span><span class="pln"> alert</span><span class="pun">(</span><span class="pln">event</span><span class="pun">.</span><span class="pln">key</span><span class="pun">)</span><span class="pln"> </span><span class="pun">}</span><span class="pln"> </span><span class="com">// Attach the function as an event listener to the "keydown" event on the input field</span><span class="pln"> document</span><span class="pun">.</span><span class="pln">getElementById</span><span class="pun">(</span><span class="str">"myInput"</span><span class="pun">).</span><span class="pln">addEventListener</span><span class="pun">(</span><span class="str">"keydown"</span><span class="pun">,</span><span class="pln"> keyPressed</span><span class="pun">);</span><span class="pln"> </span><span class="tag"></script></span><span class="pln"> </span>
You can also try below Code:
<span class="pln"> </span><span class="dec"><!DOCTYPE html></span><span class="pln"> </span><span class="tag"><html></span><span class="pln"> </span><span class="tag"><body></span><span class="pln"> </span><span class="tag"><p></span><span class="pln">This example uses the addEventListener() method to attach a "keydown" event to an input element.</span><span class="tag"></p></span><span class="pln"> </span><span class="tag"><p></span><span class="pln">Press a key inside the text field to set a red background color.</span><span class="tag"></p></span><span class="pln"> </span><span class="tag"><input</span><span class="pln"> </span><span class="atn">type</span><span class="pun">=</span><span class="atv">"text"</span><span class="pln"> </span><span class="atn">id</span><span class="pun">=</span><span class="atv">"demo"</span><span class="tag">></span><span class="pln"> </span><span class="tag"><script></span><span class="pln"> document</span><span class="pun">.</span><span class="pln">getElementById</span><span class="pun">(</span><span class="str">"demo"</span><span class="pun">).</span><span class="pln">addEventListener</span><span class="pun">(</span><span class="str">"keydown"</span><span class="pun">,</span><span class="pln"> myFunction</span><span class="pun">);</span><span class="pln"> </span><span class="kwd">function</span><span class="pln"> myFunction</span><span class="pun">()</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> document</span><span class="pun">.</span><span class="pln">getElementById</span><span class="pun">(</span><span class="str">"demo"</span><span class="pun">).</span><span class="pln">style</span><span class="pun">.</span><span class="pln">backgroundColor </span><span class="pun">=</span><span class="pln"> </span><span class="str">"red"</span><span class="pun">;</span><span class="pln"> </span><span class="pun">}</span><span class="pln"> </span><span class="tag"></script></span><span class="pln"> </span><span class="tag"></body></span><span class="pln"> </span><span class="tag"></html></span><span class="pln"> </span>
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