从匿名函数外部访问变量

Question

我试图能够在 foreach 和 readdir 函数之外获取变量 jsCss 的值。我似乎无法弄清楚。我试图将它推送到一个全局变量，但是当我记录我推送到的数组时，它仍然返回一个空数组。我该怎么做呢？

let items = [];

fs.readdir('.', (err, files) => {
    const readable = files.filter((el) => /\.vide$/.test(el));
    readable.forEach((script) => {
        let data = fs.readFileSync(script, { encoding: 'utf8' });
        const dom = htmlparser2.parseDOM(data);
        const $ = cheerio.load(dom);
        const CSS = $('Vide')
            .clone()
            .children()
            .remove()
            .end()
            .text();
        const str = css(CSS);
        let jsCss = JSON.parse(str);
        items.push(jsCss);
    })
});
console.log(items)

Answer 1

console.log 比 items.push() 更早执行，这就是你看到空数组的原因

这应该可以按您的预期工作

let items = [];

fs.readdir('.', (err, files) => {
    const readable = files.filter((el) => /\.vide$/.test(el));
    readable.forEach((script) => {
        let data = fs.readFileSync(script, { encoding: 'utf8' });
        const dom = htmlparser2.parseDOM(data);
        const $ = cheerio.load(dom);
        const CSS = $('Vide')
            .clone()
            .children()
            .remove()
            .end() //again go back to selected element
            .text();
        const str = css(CSS);
        let jsCss = JSON.parse(str);
        items.push(jsCss);
    });
    console.log(items);
});

您也可以使用readdirSync() 省略回调，如下所示：

let items = [];
const files = fs.readdirSync('.');
const readable = files.filter((el) => /\.vide$/.test(el));
readable.forEach((script) => {
    let data = fs.readFileSync(script, { encoding: 'utf8' });
    const dom = htmlparser2.parseDOM(data);
    const $ = cheerio.load(dom);
    const CSS = $('Vide')
        .clone()
        .children()
        .remove()
        .end() //again go back to selected element
        .text();
    const str = css(CSS);
    let jsCss = JSON.parse(str);
    items.push(jsCss);
});
console.log(items);