2018-10-10 22:03:03 +00:00
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---
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id: 587d7db2367417b2b2512b8b
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2021-03-15 03:20:39 +00:00
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title: 了解立即调用函数表达(IIFE)
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2018-10-10 22:03:03 +00:00
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challengeType: 1
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2020-08-04 07:15:28 +00:00
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forumTopicId: 301328
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2021-01-13 02:31:00 +00:00
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dashedName: understand-the-immediately-invoked-function-expression-iife
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2018-10-10 22:03:03 +00:00
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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2021-03-15 03:20:39 +00:00
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JavaScript 中的一个常见模式就是,函数在声明后立刻执行:
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2020-08-04 07:15:28 +00:00
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```js
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(function () {
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console.log("Chirp, chirp!");
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2021-03-15 03:20:39 +00:00
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})();
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2020-08-04 07:15:28 +00:00
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```
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2021-03-15 03:20:39 +00:00
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这是一个匿名函数表达式,立即执行并输出 `Chirp, chirp!`。
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请注意,函数没有名称,也不存储在变量中。 函数表达式末尾的两个括号()会让它被立即执行或调用。 这种模式被叫做立即调用函数表达式(<dfn>immediately invoked function expression</dfn>) 或者<dfn>IIFE</dfn>。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --instructions--
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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重写函数 `makeNest`,并删除它的调用,取而代之是一个匿名的立即调用函数表达式(IIFE)。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --hints--
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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该函数应该是匿名的。
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2018-10-10 22:03:03 +00:00
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```js
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2021-02-06 04:42:36 +00:00
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assert(/\((function|\(\))(=>|\(\)){?/.test(code.replace(/\s/g, '')));
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2018-10-10 22:03:03 +00:00
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```
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2021-03-15 03:20:39 +00:00
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函数应该在表达式的末尾有括号,以便立即调用它。
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2020-08-04 07:15:28 +00:00
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2018-10-10 22:03:03 +00:00
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```js
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2021-02-06 04:42:36 +00:00
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assert(/\(.*(\)\(|\}\(\))\)/.test(code.replace(/[\s;]/g, '')));
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2018-10-10 22:03:03 +00:00
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```
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2020-08-04 07:15:28 +00:00
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2021-01-13 02:31:00 +00:00
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# --seed--
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## --seed-contents--
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```js
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function makeNest() {
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console.log("A cozy nest is ready");
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}
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makeNest();
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```
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2020-12-16 07:37:30 +00:00
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# --solutions--
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2021-01-13 02:31:00 +00:00
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```js
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(function () {
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console.log("A cozy nest is ready");
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})();
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```
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---
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```js
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(function () {
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console.log("A cozy nest is ready");
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}());
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```
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---
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```js
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(() => {
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console.log("A cozy nest is ready");
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})();
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```
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---
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```js
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(() =>
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console.log("A cozy nest is ready")
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)();
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```
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