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docs: use let/const instead of var
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@ -9,9 +9,9 @@ async 函数是什么?一句话,它就是 Generator 函数的语法糖。
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前文有一个 Generator 函数,依次读取两个文件。
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```javascript
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var fs = require('fs');
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const fs = require('fs');
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var readFile = function (fileName) {
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const readFile = function (fileName) {
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return new Promise(function (resolve, reject) {
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fs.readFile(fileName, function(error, data) {
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if (error) return reject(error);
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@ -20,9 +20,9 @@ var readFile = function (fileName) {
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});
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};
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var gen = function* () {
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var f1 = yield readFile('/etc/fstab');
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var f2 = yield readFile('/etc/shells');
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const gen = function* () {
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const f1 = yield readFile('/etc/fstab');
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const f2 = yield readFile('/etc/shells');
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console.log(f1.toString());
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console.log(f2.toString());
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};
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@ -31,9 +31,9 @@ var gen = function* () {
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写成`async`函数,就是下面这样。
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```javascript
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var asyncReadFile = async function () {
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var f1 = await readFile('/etc/fstab');
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var f2 = await readFile('/etc/shells');
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const asyncReadFile = async function () {
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const f1 = await readFile('/etc/fstab');
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const f2 = await readFile('/etc/shells');
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console.log(f1.toString());
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console.log(f2.toString());
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};
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@ -75,8 +75,8 @@ asyncReadFile();
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```javascript
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async function getStockPriceByName(name) {
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var symbol = await getStockSymbol(name);
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var stockPrice = await getStockPrice(symbol);
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const symbol = await getStockSymbol(name);
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const stockPrice = await getStockPrice(symbol);
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return stockPrice;
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}
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@ -318,9 +318,9 @@ async function f() {
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```javascript
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async function main() {
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try {
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var val1 = await firstStep();
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var val2 = await secondStep(val1);
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var val3 = await thirdStep(val1, val2);
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const val1 = await firstStep();
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const val2 = await secondStep(val1);
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const val3 = await thirdStep(val1, val2);
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console.log('Final: ', val3);
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}
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@ -503,7 +503,7 @@ function fn(args) {
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```javascript
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function spawn(genF) {
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return new Promise(function(resolve, reject) {
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var gen = genF();
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const gen = genF();
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function step(nextF) {
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try {
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var next = nextF();
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@ -536,13 +536,13 @@ function spawn(genF) {
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function chainAnimationsPromise(elem, animations) {
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// 变量ret用来保存上一个动画的返回值
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var ret = null;
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let ret = null;
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// 新建一个空的Promise
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var p = Promise.resolve();
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let p = Promise.resolve();
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// 使用then方法,添加所有动画
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for(var anim of animations) {
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for(let anim of animations) {
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p = p.then(function(val) {
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ret = val;
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return anim(elem);
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@ -567,9 +567,9 @@ function chainAnimationsPromise(elem, animations) {
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function chainAnimationsGenerator(elem, animations) {
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return spawn(function*() {
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var ret = null;
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let ret = null;
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try {
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for(var anim of animations) {
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for(let anim of animations) {
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ret = yield anim(elem);
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}
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} catch(e) {
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@ -587,9 +587,9 @@ function chainAnimationsGenerator(elem, animations) {
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```javascript
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async function chainAnimationsAsync(elem, animations) {
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var ret = null;
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let ret = null;
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try {
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for(var anim of animations) {
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for(let anim of animations) {
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ret = await anim(elem);
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}
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} catch(e) {
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