Javascript get x and y coordinates on mouse click

Breaking down the MouseEvent object

Getting mouse coordinates involves the MouseEvent object and its properties, specifically clientX, clientY, pageX, and pageY.

• clientX and clientY give you viewport-relative coordinates. They remain constant even when you scroll.
• pageX and pageY provide page-relative coordinates. If they return undefined, probably your browser had a rough day and can't handle those properties, and you should stick with clientX and clientY.

function printMousePos(e) {
    // Who needs GPS when you've got this?
    console.log(`Page Coords: X = ${e.pageX}, Y = ${e.pageY}`);
    console.log(`Client Coords: X = ${e.clientX}, Y = ${e.clientY}`);
}
// Event listener: not as scary as it sounds.
document.addEventListener('click', printMousePos, false);
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Simplifying and Ensuring Compatibility

Keep things simple and stick with clientX and clientY for browser compatibility. For coordinates relative to the event-triggering element, consider using event.offsetX and event.offsetY.

function getElementRelativeCoords(event) {
    // No, it's not a spell from Harry Potter. It's just JavaScript. 
    console.log(`Element Coords: X = ${event.offsetX},Y = ${event.offsetY}`);
}
document.addEventListener('click', getElementRelativeCoords);
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If you're creating a dynamic UI that needs to snipe mouse coordinates in real-time, go ahead with:

// Feels like Minority Report, doesn't it?
document.onmousemove = (e) => {
    document.getElementById("liveCoords").textContent = `X = ${e.clientX}, Y = ${e.clientY}`;
};
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Event Handling in Complex Scenarios

When implementing mouse coords in more complex applications like games, keep a few things in mind:

• Ensure your function is globally accessible
• Test across different browsers for compatibility
• Check for interference from other scripts impacting event handling

And don't forget to account for scrolling when using pageX and pageY, because the scrolling distance from the viewport top affects these values.

Debugging Your Implementation

If your mouse coords seem to be playing hide and seek, check the following:

• Is your game.js file running correctly?
• Any conflicting scripts causing an epic event-handling standoff?
• Have a peek at your browser's console for potential clues.

Showing coordinates to users

Wanna show off your freshly caught mouse coordinates to users? Here you go:

document.addEventListener('click', function(event) {
    let coordDisplay = document.getElementById("coordDisplay");
    coordDisplay.textContent = `X = ${event.clientX}, Y = ${event.clientY}`;
});
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Here, we use an element with ID coordDisplay to showcase the magical coordinates with each click.

Dealing with CSS and Responsive Design

When mapping mouse coordinates, don't overlook CSS styles and responsive design. Implementing UI features based on coordinates requires factoring in screen size, resolution, margins, borders, and padding to get the 'spot-on' click location. Remember, with the power of coordinates, comes coding responsibilities!.