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promise封装的ajax + rem布局

作者：筱闯~ 更新时间： 2023-07-14 编程语言

首先是html文件

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<script src="./rem.js"></script>
<script src="./promise封装.js"> </script>
<style>
    *{
        margin: 0;
        padding: 0;
    }
</style>
<body>
    <div style="width: 2rem; height: 2rem; background-color: #409EFF;">
        <div style="width: 1rem; height: 1rem; background-color: #c00;">
            <div style="font-size: 0.3rem;">页面</div>
        </div>
    </div>
</body>
<script>
    window.onload = function(){
        console.log(request);
        request("https://elm.cangdu.org/v1/cities?type=guess").then((res)=>{
            console.log(res);
        })
    }
</script>

</html>

其次是rem.js

window.onresize = function() {
    console.log("尺寸发生改变");
    getRem()
}
getRem()
function getRem(){
    let html = document.querySelector("html")
    let oWidth = document.documentElement.clientWidth
    // 375页面的宽度
    html.style.fontSize = oWidth/375*100 + "px"
}

最后是promise封装的ajax

promise 是用来解决异步操作的含有三个属性成功，失败和进行中

function request (url,motheds="GET"){
    return new Promise((resolve, reject) => {
        //原生ajax
        var xhr;
        if(window.XMLHttpRequest){
            xhr = new XMLHttpRequest()
        }else{
            xhr = new ActiveXObject("Microsoft.XMLHTTP")
        }
        xhr.onreadystatechange = function(){
            resolve('先')
            if(xhr.readyState == 4 && xhr.status == 200){
                let data = xhr.responseText
                console.log(data);
            }
        }
        xhr.open(motheds,url,true)
        xhr.send(null)
    })
}

原文链接：https://blog.csdn.net/m0_64544033/article/details/130760433

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promise封装的ajax + rem布局

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