私密图片，请求图片时需要鉴权

import { hex_md5 } from 'md5';
function getCookie(name, defaultValue) {
    let arr, reg = new RegExp("(^| )" + name + "=([^;]*)(;|$)");
    if (arr = document.cookie.match(reg)) return unescape(arr[2]);
    else return defaultValue;
}
let requestImage = function (url, element) {
    let request = new XMLHttpRequest();
    request.responseType = 'blob';
    request.open('get', url, true);
    let token = getCookie("token") || "",
        timestamp = String((new Date()).getTime()),
        securt = "your securt",
        sign = hex_md5(`AUTH-TIMESTAMP=${timestamp}&AUTH-TOKEN=${token}#${securt}`);
    request.setRequestHeader('AUTH-SIGN', sign);
    request.setRequestHeader('AUTH-TIMESTAMP', timestamp);
    request.setRequestHeader('AUTH-TOKEN', token);
    request.onreadystatechange = e => {
        if (request.readyState == XMLHttpRequest.DONE && request.status == 200) {
            if (request.response.type == 'image/jpeg' || request.response.type == 'image/png' || request.response.type == 'image/jpg') {
                element.src = URL.createObjectURL(request.response);
                element.style.display = "block";
                // element.part = "native";
                element.onload = () => {
                    URL.revokeObjectURL(element.src);
                }
            } else {
                element.src = "";
                element.style.display = "none";
            }
        } else {
            element.src = "";
            element.style.display = "none";
        }
    };
    request.send(null);
}
class AuthImg extends HTMLElement {
    constructor() {
        super();
        this.img = new Image();
        const shadow = this.attachShadow({ mode: 'open' });
        // shadow.innerHTML = ``; // 添加dom结构
        shadow.appendChild(this.img);
    }
    // 监听属性修改
    static get observedAttributes() { return ['auth-src', 'style', 'class']; }
    // 生命周期钩子函数
    connectedCallback() {
        // if(this.img == null){
        //   this.img = new Image();
        //   const shadow = this.attachShadow({ mode: 'open'});
        //   shadow.appendChild(this.img);
        // }
        requestImage(this.getAttribute('auth-src'), this.img);
        if (this.getAttribute("style")) {
            this.img.setAttribute("style", this.getAttribute("style"));
        }
        if (this.getAttribute("class")) {
            this.img.className = this.getAttribute("class");
        }
    }
    attributeChangedCallback(name, oldValue, newValue) {
        if (name == 'auth-src' && (oldValue !== null && newValue !== oldValue)) {
            requestImage(this.getAttribute('auth-src'), this.img);
        } else if (name == 'style') {
            this.img.setAttribute("style", this.getAttribute("style"));
        } else if (name == 'class') {
            this.img.className = this.getAttribute("class");
        }
    }
    disconnectedCallback() {
        // const shadow = this.attachShadow({ mode: 'open'});
        // shadow.removeChild(this.img);      
        this.img.src = '';
    }
}
window.customElements.define('auth-img', AuthImg); // 定义自定义标签名称

使用方法

<img is="auth-img" auth-src="xxx.jpg">

官方文档：https://developers.google.cn/web/fundamentals/web-components/
参考文章：
https://github.com/linpenghui958/note/blob/master/WebComponents.md
https://zhuanlan.zhihu.com/p/150268517?from_voters_page=true