题目：利用 XMLHttpRequest 手写 AJAX 实现
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| function getAjax (url) {
return new Promise((resolve, reject) => {
const xhr = new XMLHttpRequest();
xhr.open('GET', url, false);
xhr.setRequestHeader("Content-Type", "application/json");
xhr.onreadystatechange = function () {
if (xhr.readyState !== 4) return;
if (xhr.status === 200 || xhr.status ===304) {
resolve(xhr.responseText);
} else {
reject(new Error(xhr.responseText));
}
};
xhr.send();
});
};
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getAjax('https://www.baidu.com');
|
结果：
