Javascript onunload表单提交未提交数据

window.onunload = function() {
    var formData = new FormData(document.getElementById('myForm'));
    var xhr = new XMLHttpRequest();
    xhr.open('POST', '/submit', false); // 第三个参数设置为 false 表示同步请求
    xhr.send(formData);
};

window.onbeforeunload = function() {
    var formData = new FormData(document.getElementById('myForm'));
    var xhr = new XMLHttpRequest();
    xhr.open('POST', '/submit');
    xhr.send(formData);
};

window.onunload = function() {
    var formData = new FormData(document.getElementById('myForm'));
    localStorage.setItem('formData', JSON.stringify(Object.fromEntries(formData)));
};

window.onload = function() {
    var savedData = JSON.parse(localStorage.getItem('formData'));
    if (savedData) {
        // 提交数据
        localStorage.removeItem('formData');
    }
};