我的坐標是NaN，NaN

Question

我正在嘗試獲取鼠標在畫布上的位置坐標。 但我回來的只是NaN，NaN

var canvasBg = document.getElementById('canvasBg');
var ctxBg = canvasBg.getContext('2d');

var mouseX;
var mouseY;

canvasBg.addEventListener('mousemove', mouseMoved, false);
canvasBg.addEventListener('click', mouseClicked, false);

function mouseMoved(e) {

mouseX = e.pageX - canvasBg.pageOffsetLeft;
mouseY = e.pageY - canvasBg.pageOffsetTop;
document.getElementById('mouseCoors').innerHTML = 'X: ' + mouseX + ' Y: ' + mouseY;

}

function mouseClicked(e) {

    alert( mouseX + "," + mouseY);

}

Answer 1

您可以通過以下方式簡化操作：

function mouseMoved(e) {
    mouseX = e.offsetX;
    mouseY = e.offsetY;
    document.getElementById('mouseCoors').innerHTML = 'X: ' + mouseX + ' Y: ' + mouseY;
}

function mouseClicked(e) {
    alert( e.offsetX + "," + e.offsetY);
}

Answer 2

這是另一個解決方案！

為您的mouseMoved函數嘗試以下操作：

function mouseMoved(e) {
    mouseX = e.x - canvasBg.offsetLeft;
    mouseY = e.y - canvasBg.offsetTop;

    document.getElementById('mouseCoors').innerHTML = 'X: ' + mouseX + ' Y: ' + mouseY;
}

完整代碼的實時預覽： Fiddle 。

參考