Tailwind CSS 源代码中的 String.raw。

本文我们分析一下Tailwindcss源码中String.raw的用法。

String.raw

MDN 文档说：

“String.raw()静态方法是模板文字的标签函数。

这类似于 Python 中的 r 前缀，或 C# 中字符串文字的 @ 前缀。

它用于获取模板文字的原始字符串形式 - 即替换

（例如 ${foo}）被处理，但转义序列（例如 n）未被处理。“

示例1：

以下示例摘自MDN：

// Create a variable that uses a Windows
// path without escaping the backslashes:
const filePath = String.raw`C:\Development\profile\aboutme.html`;
console.log(`The file was uploaded from: ${filePath}`);
// Expected output: "The file was uploaded from: C:\Development\profile\aboutme.html"

上面示例的执行结果如下所示：

> "The file was uploaded from: C:\Development\profile\aboutme.html"

示例2：

如果您使用以下代码在没有 String.raw 的情况下运行相同的示例：

// Create a variable that uses a Windows
// path without escaping the backslashes:
const filePath = `C:\Development\profile\aboutme.html`;
console.log(`The file was uploaded from: ${filePath}`);
// Expected output: "The file was uploaded from: C:\Development\profile\aboutme.html"

结果如下所示：

> "The file was uploaded from: C:Developmentprofileaboutme.html"

示例3：

如果您使用以下代码运行涉及 n 的相同示例：

const filePathWithoutStringRaw = `\nC:\Development\profile\aboutme.html`;
const filePathWithStringRaw = String.raw`\nC:\Development\profile\aboutme.html`;
console.log("filePathWithoutStringRaw:", filePathWithoutStringRaw)
console.log("*******")
console.log("filePathWithStringRaw:", filePathWithStringRaw)

结果如下所示：

> "filePathWithoutStringRaw:" "
C:Developmentprofileaboutme.html"
> "*******"
> "filePathWithStringRaw:" "\nC:\Development\profile\aboutme.html"

Tailwindcss 如何使用 String.raw：

ui.spec.ts 测试文件将 String.raw 分配给 html 和 css。

发现很多用ui.spec.ts编写的测试都使用了html

让我们仔细看看这个测试代码：

for (let [classes, expected] of [
 [
 'bg-linear-to-r from-red-500',
 'linear-gradient(to right, rgb(239, 68, 68) 0%, rgba(0, 0, 0, 0) 100%)',
 ],
 [
 'bg-linear-to-r via-red-500',
 'linear-gradient(to right, rgba(0, 0, 0, 0) 0%, rgb(239, 68, 68) 50%, rgba(0, 0, 0, 0) 100%)',
 ],
 [
 'bg-linear-to-r to-red-500',
 'linear-gradient(to right, rgba(0, 0, 0, 0) 0%, rgb(239, 68, 68) 100%)',
 ],
 [
 'bg-linear-to-r from-red-500 to-blue-500',
 'linear-gradient(to right, rgb(239, 68, 68) 0%, rgb(59, 130, 246) 100%)',
 ],
 [
 'bg-linear-to-r via-red-500 to-blue-500',
 'linear-gradient(to right, rgba(0, 0, 0, 0) 0%, rgb(239, 68, 68) 50%, rgb(59, 130, 246) 100%)',
 ],
 [
 'bg-linear-to-r from-red-500 via-green-500 to-blue-500',
 'linear-gradient(to right, rgb(239, 68, 68) 0%, rgb(34, 197, 94) 50%, rgb(59, 130, 246) 100%)',
 ],
 [
 'bg-linear-[to_right,var( - color-red-500),var( - color-green-500),var( - color-blue-500)]',
 'linear-gradient(to right, rgb(239, 68, 68), rgb(34, 197, 94), rgb(59, 130, 246))',
 ],
]) {
 test(`background gradient, "${classes}"`, async ({ page }) => {
   let { getPropertyValue } = await render(
   page,
   html`<div id="x" class="${classes}">Hello world</div>`,
   )
   expect(await getPropertyValue('#x', 'background-image')).toEqual(expected)
 })
}

看到在 for 循环中定义的整个数组很有趣。

html`<div id="x" class="${classes}">Hello world</div>`,

${classes} 被替换为以下数组的第一项：

[<br>
 'bg-linear-to-r from-red-500',<br>
 'linear-gradient(to right, rgb(239, 68, 68) 0%, rgba(0, 0, 0, 0) 100%)',<br>
],<br>

关于我们：

在 Think Throo，我们的使命是教授开源项目中使用的高级代码库架构概念。

通过在 Next.js/React 中练习高级架构概念，将您的编码技能提高 10 倍，学习最佳实践并构建生产级项目。

我们是开源的 — https://github.com/thinkthroo/thinkthroo （请给我们一颗星！）

我们还提供网络开发和技术写作服务。请通过hello@thinkthroo.com联系我们了解更多信息！

参考文献：

1. https://github.com/tailwindlabs/tailwindcss/blob/next/packages/tailwindcss/tests/ui.spec.ts

2. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/raw

3. https://stackoverflow.com/questions/34772762/what-are-the-actual-uses-of-es6-raw-string-access

以上是Tailwind CSS 源代码中的 String.raw。的详细内容。更多信息请关注PHP中文网其他相关文章！