ajax简单用法

请求端

<body>
    <div> hello world</div>
    <input type="button" value="ajax">
</body>
<style>
    div {
        width: 200px;
        height: 300px;
        border: aquamarine 1px solid;
    }
</style>
<script>
    let bt = document.querySelector("input");
    let mydiv = document.querySelector("div");
    bt.onclick = function () {
        let xhr = new XMLHttpRequest();
        console.log(xhr.readyState);
        xhr.open("get", "http://localhost:8000/");
        console.log(xhr.readyState);
        xhr.send();
        xhr.onreadystatechange = function () {
            if (xhr.readyState === 4) {
                if (xhr.status >= 200 && xhr.status <= 300) {
                    console.log("success");
                    console.log(xhr.status);
                    console.log(xhr.readyState);
                    console.log(xhr.statusText);
                    console.log(xhr.response);
                    console.log(xhr.getAllResponseHeaders());
                    mydiv.innerHTML = xhr.response;
                }
            }
        }
    }
</script>

服务器端

let express = require("express");
let app1 = express();
app1.get("/", (r, rs) => {
    rs.setHeader("Access-Control-Allow-Origin", "*")
    rs.send("收到")
})
app1.listen(8000, () => {
    console.log(
        "8000服务器启动"
    );
})
posted @ 2021-08-02 20:51  贾正直  阅读(29)  评论(0)    收藏  举报