When you encounter an error message like “cannot read properties of undefined (reading ‘preventdefault’)”, it means that you are trying to access the property “preventdefault” of an object that is undefined or null. This error commonly occurs when you call preventDefault() on an event object that is undefined or null.
To understand this error better, let’s consider an example:
<button onclick="handleClick()">Click me</button>
<script>
function handleClick(event) {
event.preventDefault(); // This line will throw an error if event is undefined
alert("Button clicked");
}
</script>
In the above example, the handleClick function is called when the button is clicked. However, the function expects an event object as a parameter, but we haven’t passed any parameter to it. As a result, the event inside the function is undefined, and when preventDefault() is called on an undefined object, the error “cannot read properties of undefined (reading ‘preventdefault’)” is thrown.
To fix this error, you should make sure that you are passing the event object to the function. Here’s an updated example:
<button onclick="handleClick(event)">Click me</button>
<script>
function handleClick(event) {
event.preventDefault();
alert("Button clicked");
}
</script>
In the updated example, we pass the event object to the handleClick function by adding the “event” parameter in the onclick attribute of the button. Now, the preventDefault() method will be called on a valid event object, and the error will be resolved.
It’s important to ensure that the event object is defined and passed correctly in scenarios where you want to interact with it, such as accessing its properties or calling its methods like preventDefault().