js获取div高度和宽度

// 获取元素
var div = document.getElementById('myDiv');

// 使用 offsetHeight 和 offsetWidth
var heightOffset = div.offsetHeight;
var widthOffset = div.offsetWidth;

// 使用 clientHeight 和 clientWidth
var heightClient = div.clientHeight;
var widthClient = div.clientWidth;

// 使用 getBoundingClientRect()
var rect = div.getBoundingClientRect();
var heightRect = rect.height;
var widthRect = rect.width;

console.log("offsetHeight: " + heightOffset);
console.log("offsetWidth: " + widthOffset);
console.log("clientHeight: " + heightClient);
console.log("clientWidth: " + widthClient);
console.log("getBoundingClientRect height: " + heightRect);
console.log("getBoundingClientRect width: " + widthRect);

window.onload = function() {
    var div = document.getElementById('myDiv');
    console.log(div.offsetHeight);
};

// 或者使用 requestAnimationFrame
function checkSize() {
    var div = document.getElementById('myDiv');
    console.log(div.offsetHeight);
    requestAnimationFrame(checkSize);
}
requestAnimationFrame(checkSize);