最佳实践

图片加载失败时

img特性：图片正常加载时，伪元素会失效；但如果加载失败，伪元素会生效

占位符

• HTML

<img src="url.png" alt="CSS处理加载失败占位符" />

• CSS

img {
    display: inline-block;
    transform: scale(1);
}

img::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background: #f5f5f5 url(break.svg) no-repeat center / 50% 50%;
    color: transparent;
}

img::after {
    content: attr(alt);
    position: absolute;
    left: 0;
    bottom: 0;
    width: 100%;
    line-height: 2;
    background: rgba(0, 0, 0, .5);
    color: #fff;
    font-size: 14px;
    text-align: center;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

没头像时使用名字的首字母

• CSS

img.avatar {
    display: inline-block;
    --s: var(--size,1.5rem);
    width: var(--s);
    height: var(--s);
    border-radius: 50%;
    white-space: normal;
    overflow: hidden;
}

img.avatar::before {
    content: attr(alt);
    display: flex;
    font-size: calc(var(--s)*.5);
    width: 100%;
    height: 100%;
    background-color: bisque;
    line-height: var(--s);
    letter-spacing: var(--s);
    text-indent: var(--s);
    justify-content: center;
    text-align: center;
    color: inherit;
    line-break: anywhere;
}