{"id":2485,"date":"2020-03-25T11:52:09","date_gmt":"2020-03-25T03:52:09","guid":{"rendered":"http:\/\/www.yuguoxy.com\/geekhome\/?p=2485"},"modified":"2026-08-18T12:35:25","modified_gmt":"2026-08-18T04:35:25","slug":"js%e6%95%b0%e7%bb%84%e5%b8%b8%e7%94%a8%e9%81%8d%e5%8e%86%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/ai.zhousir.top\/?p=2485","title":{"rendered":"js\u6570\u7ec4\u5e38\u7528\u904d\u5386\u65b9\u6cd5"},"content":{"rendered":"
\n

\u6570\u7ec4\u5e38\u7528\u904d\u5386\u65b9\u6cd5\u5305\u62ec forEach<\/code>\u3001map<\/code>\u3001filter<\/code>\u3001find<\/code>\u3001every<\/code>\u3001some<\/code>\u3001reduce<\/code>\u3002\u5b83\u4eec\u6709\u4e2a\u5171\u540c\u70b9\uff1a\u4e0d\u4f1a\u6539\u539f\u59cb\u6570\u7ec4<\/strong>\uff08\u5f53\u7136\uff0c\u5982\u679c\u4f60\u5728\u56de\u8c03\u91cc\u6539\u5bf9\u8c61\u5c5e\u6027\uff0c\u90a3\u662f\u53e6\u4e00\u56de\u4e8b\uff09\u3002<\/p>\n

\u548c for<\/code> \u5faa\u73af\u76f8\u6bd4\uff0c\u8fd9\u4e9b\u65b9\u6cd5\u628a\u201c\u904d\u5386\u201d\u548c\u201c\u8981\u505a\u4ec0\u4e48\u201d\u62c6\u5f00\uff0c\u56de\u8c03\u91cc\u4e13\u6ce8\u5355\u6761\u6570\u636e\u3002forEach<\/code> \u6ca1\u6709\u8fd4\u56de\u503c\uff1bmap<\/code> \u5fc5\u987b\u6709\u8fd4\u56de\u503c\uff0c\u5fd8\u4e86 return<\/code> \u5c31\u4f1a\u5f97\u5230 undefined<\/code>\u3002<\/p>\n

\u4e00\u3001forEach\uff1a\u904d\u5386\u6570\u7ec4<\/h2>\n

\u5148\u5bf9\u6bd4 ES5 \u7684\u4e0b\u6807\u5faa\u73af\u548c ES6 \u7684 forEach\uff0c\u8f93\u51fa\u540c\u6837\u662f red \/ blue \/ green\uff1a<\/p>\n

var colors = [\"red\",\"blue\",\"green\"];\n\n\/\/ ES5\u904d\u5386\u6570\u7ec4\u65b9\u6cd5\n\nfor(var i = 0; i < colors.length; i++){ \n\n console.log(colors[i]);\/\/red blue green\n\n}\n\n\/\/ ES6 forEach\n\ncolors.forEach(function(color){\n\n console.log(color);\/\/red blue green\n\n});<\/code><\/pre>\n
\u518d\u770b\u4e00\u4e2a\u7d2f\u52a0\uff1a\u904d\u5386\u6570\u7ec4\u4e2d\u7684\u503c\u5e76\u8ba1\u7b97\u603b\u548c\u3002<\/p>\n
var numbers = [1,2,3,4,5];\n\nvar sum = 0;\n\nnumbers.forEach(number=>sum+=number)\n\nconsole.log(sum)\/\/15<\/code><\/pre>\n
\u4e8c\u3001map\uff1a\u6620\u5c04\u6210\u53e6\u4e00\u4e2a\u6570\u7ec4<\/h2>\n
map<\/strong> \u7528\u6307\u5b9a\u51fd\u6570\u5904\u7406\u6bcf\u4e2a\u5143\u7d20\uff0c\u8fd4\u56de\u5904\u7406\u540e\u7684\u65b0\u6570\u7ec4\uff0c\u4e0d\u6539\u539f\u6570\u7ec4\u3002forEach \u548c map \u7684\u533a\u522b<\/strong>\u5728\u4e8e forEach \u6ca1\u6709\u8fd4\u56de\u503c\uff1bmap \u9700\u8981\u8fd4\u56de\u503c\u3002<\/p>\n
\u4f7f\u7528\u573a\u666f 1\uff1a\u6570\u503c\u7ffb\u500d<\/h3>\n
\u5047\u5b9a\u6709\u6570\u503c\u6570\u7ec4 A\uff0c\u628a A \u4e2d\u7684\u503c\u4ee5\u53cc\u500d\u5f62\u5f0f\u653e\u5230 B \u6570\u7ec4\uff1a<\/p>\n
var numbers = [1,2,3];\n\nvar doubledNumbers = [];\n\n\/\/ es5\u5199\u6cd5\n\nfor(var i = 0; i < numbers.length; i++){\n\n doubledNumbers.push(numbers[i] * 2);\n\n}\n\nconsole.log(doubledNumbers);\/\/[2,4,6]\n\n\/\/ es6 map\u65b9\u6cd5\n\nvar doubled = numbers.map(function(number){\n\n   return number * 2;\n\n})\n\nconsole.log(doubled);\/\/[2,4,6]<\/code><\/pre>\n
\u4f7f\u7528\u573a\u666f 2\uff1a\u62bd\u51fa\u5bf9\u8c61\u5c5e\u6027<\/h3>\n
\u5047\u5b9a\u6709\u5bf9\u8c61\u6570\u7ec4 A\uff0c\u628a\u67d0\u4e2a\u5c5e\u6027\u5b58\u5230 B \u6570\u7ec4\uff1a<\/p>\n
var cars = [\n\n  {model:\"Buick\",price:\"CHEAP\"},\n\n  {model:\"BMW\",price:\"expensive\"}\n\n];\n\nvar prices = cars.map(function(car){\n\n    return car.price;\n\n})\n\nconsole.log(prices);\/\/[\"CHEAP\", \"expensive\"]<\/code><\/pre>\n
\u4e09\u3001filter\uff1a\u627e\u51fa\u6240\u6709\u7b26\u5408\u6761\u4ef6\u7684\u5143\u7d20<\/h2>\n
filter()<\/code> \u68c0\u6d4b\u5143\u7d20\u5e76\u8fd4\u56de\u7b26\u5408\u6761\u4ef6\u7684\u65b0\u6570\u7ec4\uff0c\u4e0d\u6539\u539f\u6570\u7ec4\u3002<\/p>\n
\u4f7f\u7528\u573a\u666f 1\uff1a\u6309\u7c7b\u578b\u7b5b\u9009<\/h3>\n
\u4ece\u5bf9\u8c61\u6570\u7ec4\u91cc\u53d6\u51fa\u6307\u5b9a type \u653e\u5230\u65b0\u6570\u7ec4\u3002\u539f\u6587\u53d8\u91cf\u540d porducts<\/code> \u4fdd\u6301\u4e0d\u53d8\u3002<\/p>\n
var porducts = [\n\n  {name:\"cucumber\",type:\"vegetable\"},\n\n  {name:\"banana\",type:\"fruit\"},\n\n  {name:\"celery\",type:\"vegetable\"},\n\n  {name:\"orange\",type:\"fruit\"}\n\n];\n\n\/\/ es5\u5199\u6cd5\n\nvar filteredProducts = [];\n\nfor(var i = 0; i < porducts.length; i++){\n\n    if(porducts[i].type === \"vegetable\"){\n\n      filteredProducts.push(porducts[i]);\n\n    }\n\n}\n\nconsole.log(filteredProducts);\/\/[{name: \"cucumber\", type: \"vegetable\"},\n\n                                 {name: \"celery\", type: \"vegetable\"}]\n\n\/\/ es6 filter\n\nvar filtered2 = porducts.filter(function(product){\n\n  return product.type === \"vegetable\";\n\n})\n\nconsole.log(filtered2);<\/code><\/pre>\n
\u4f7f\u7528\u573a\u666f 2\uff1a\u591a\u6761\u4ef6\u8fc7\u6ee4<\/h3>\n
\u852c\u83dc\u3001\u6570\u91cf\u5927\u4e8e 0\u3001\u4ef7\u683c\u5c0f\u4e8e 10\uff1a<\/p>\n
var products = [\n\n  {name:\"cucumber\",type:\"vegetable\",quantity:0,price:1},\n\n  {name:\"banana\",type:\"fruit\",quantity:10,price:16},\n\n  {name:\"celery\",type:\"vegetable\",quantity:30,price:8},\n\n  {name:\"orange\",type:\"fruit\",quantity:3,price:6}\n\n];\n\nproducts = products.filter(function(product){\n\n    return product.type === \"vegetable\" \n\n    && product.quantity > 0 \n\n    && product.price < 10\n\n})\n\nconsole.log(products);\/\/[{name:\"celery\",type:\"vegetable\",quantity:30,price:8}]<\/code><\/pre>\n
\u4f7f\u7528\u573a\u666f 3\uff1a\u6309\u5173\u8054 id \u8fc7\u6ee4<\/h3>\n
\u6839\u636e A \u4e2d id\uff0c\u8fc7\u6ee4 B \u6570\u7ec4\u4e0d\u7b26\u5408\u7684\u6570\u636e\uff1a<\/p>\n
var post = {id:4,title:\"Javascript\"};\n\nvar comments = [\n\n   {postId:4,content:\"Angular4\"},\n\n   {postId:2,content:\"Vue.js\"},\n\n   {postId:3,content:\"Node.js\"},\n\n   {postId:4,content:\"React.js\"},\n\n];\n\nfunction commentsForPost(post,comments){\n\n   return comments.filter(function(comment){\n\n     return comment.postId === post.id;\n\n   })\n\n}\n\nconsole.log(commentsForPost(post,comments));\/\/[{postId:4,content:\"Angular4\"},{postId:4,content:\"React.js\"}]<\/code><\/pre>\n
\u56db\u3001find\uff1a\u7b2c\u4e00\u4e2a\u901a\u8fc7\u6d4b\u8bd5\u7684\u5143\u7d20<\/h2>\n
\u53c2\u6570\u662f\u56de\u8c03\uff0c\u6210\u5458\u4f9d\u6b21\u6267\u884c\uff0c\u76f4\u5230\u627e\u51fa\u7b2c\u4e00\u4e2a\u8fd4\u56de true \u7684\u6210\u5458\u5e76\u8fd4\u56de\u5b83\uff1b\u6ca1\u6709\u5219 undefined<\/code>\u3002\u627e\u5230\u540e\u5373\u7ec8\u6b62\uff0c\u548c\u5e26 break<\/code> \u7684 for \u4e00\u6837\u3002<\/p>\n
\u4f7f\u7528\u573a\u666f 1\uff1a\u6309\u540d\u5b57\u627e\u5bf9\u8c61<\/h3>\n
var users = [\n\n  {name:\"Jill\"},\n\n  {name:\"Alex\",id:2},\n\n  {name:\"Bill\"},\n\n  {name:\"Alex\"}\n\n ];\n\n\/\/ es5\u65b9\u6cd5\n\n var user;\n\n for(var i = 0; i < users.length; i++){\n\n  if(users[i].name === \"Alex\"){\n\n    user = users[i];\n\n    break;\/\/\u627e\u5230\u540e\u5c31\u7ec8\u6b62\u5faa\u73af\n\n  }\n\n }\n\n console.log(user);\/\/ {name:\"Alex\",id:2}\n\n\/\/ es6 find\n\nuser = users.find(function(user){\n\n  return user.name === \"Alex\";\n\n})\n\nconsole.log(user);\/\/ {name:\"Alex\",id:2}\u627e\u5230\u540e\u5c31\u7ec8\u6b62\u5faa\u73af<\/code><\/pre>\n
\u4f7f\u7528\u573a\u666f 2\uff1a\u6309\u8bc4\u8bba\u53cd\u67e5\u5e16\u5b50<\/h3>\n
var posts = [\n\n {id:3,title:\"Node.js\"},\n\n {id:1,title:\"React.js\"}\n\n];\n\nvar comment = {postId:1,content:\"Hello World!\"};\n\nfunction postForComment(posts,comment){\n\n return posts.find(function(post){\n\n   return post.id === comment.postId;\n\n })\n\n}\n\nconsole.log(postForComment(posts,comment));\/\/{id: 1, title: \"React.js\"}<\/code><\/pre>\n
\u4e94\u3001every \u4e0e some<\/h2>\n
every<\/strong>\uff1a\u662f\u5426\u6bcf\u4e2a\u5143\u7d20\u90fd\u6ee1\u8db3\u6761\u4ef6\u3002some<\/strong>\uff1a\u662f\u5426\u6709\u5143\u7d20\u6ee1\u8db3\u6761\u4ef6\u3002Some\uff1a\u4e00\u771f\u5373\u771f\uff1bEvery\uff1a\u4e00\u5047\u5373\u5047\u3002<\/strong><\/p>\n
\u4f7f\u7528\u573a\u666f 1\uff1a\u7535\u8111\u5185\u5b58\u662f\u5426\u591f\u8dd1\u7a0b\u5e8f<\/h3>\n
\u5927\u4e8e 16 \u4f4d\uff08\u539f\u6587\u7528 ram > 16 \u8868\u793a\u53ef\u7528\uff09\u3002\u6ce8\u610f ES5 \u624b\u5199\u5faa\u73af\u7528\u7684\u662f ram < 16<\/code> \u5224\u4e0d\u53ef\u7528\uff0cES6 \u793a\u4f8b\u5199\u6210 ram > 16<\/code>\uff0cApple \u7684 16 \u5728 every \u91cc\u4f1a\u5931\u8d25\uff0c\u548c\u201c\u5927\u4e8e 16 \u624d\u53ef\u7528\u201d\u7684\u6587\u5b57\u4e00\u81f4\u3002<\/p>\n
\/\/ES5\u65b9\u6cd5\n\nvar computers = [\n\n {name:\"Apple\",ram:16},\n\n {name:\"IBM\",ram:4},\n\n {name:\"Acer\",ram:32}\n\n];\n\nvar everyComputersCanRunProgram = true;\n\nvar someComputersCanRunProgram = false;\n\nfor(var i = 0; i < computers.length; i++){\n\n var computer = computers[i];\n\n if(computer.ram < 16){\n\n   everyComputersCanRunProgram = false;\n\n }else{\n\n   someComputersCanRunProgram = true;\n\n }\n\n}\n\nconsole.log(everyComputersCanRunProgram);\/\/false\n\nconsole.log(someComputersCanRunProgram);\/\/true\n\n\/\/ES6 some every \n\nvar every = computers.every(function(computer){\n\n  return computer.ram > 16;\n\n})\n\nconsole.log(every);\/\/false\n\nvar some = computers.some(function(computer){\n\n return computer.ram > 16;\n\n})\n\nconsole.log(some);\/\/true<\/code><\/pre>\n
\u4f7f\u7528\u573a\u666f 2\uff1a\u6ce8\u518c\u8868\u5355\u6bcf\u4e00\u9879\u90fd\u975e\u7a7a<\/h3>\n
\u5224\u65ad\u6240\u6709 input \u5185\u5bb9\u957f\u5ea6\u662f\u5426\u5927\u4e8e 0\uff1a<\/p>\n
function Field(value){\n\n  this.value = value;\n\n}\n\nField.prototype.validate = function(){\n\n  return this.value.length > 0;\n\n}\n\n\/\/ES5\u65b9\u6cd5\n\nvar username = new Field(\"henrywu\");\n\nvar telephone = new Field(\"18888888888\");\n\nvar password = new Field(\"my_password\");\n\nconsole.log(username.validate());\/\/true\n\nconsole.log(telephone.validate());\/\/true\n\nconsole.log(password.validate());\/\/true\n\n\/\/ES6 some every\n\nvar fields = [username,telephone,password];\n\nvar formIsValid = fields.every(function(field){\n\n return field.validate();\n\n})\n\nconsole.log(formIsValid);\/\/true\n\nif(formIsValid){\n\n \/\/ \u6ce8\u518c\u6210\u529f\n\n}else{\n\n  \/\/ \u7ed9\u7528\u6237\u4e00\u4e2a\u53cb\u5584\u7684\u9519\u8bef\u63d0\u9192\n\n}<\/code><\/pre>\n
\u516d\u3001reduce\uff1a\u5408\u6210\u4e00\u4e2a\u503c<\/h2>\n
reduce()<\/code> \u63a5\u6536\u7d2f\u52a0\u5668\u51fd\u6570\uff0c\u4ece\u5de6\u5230\u53f3\u5408\u5e76\uff0c\u6700\u7ec8\u6210\u4e3a\u4e00\u4e2a\u503c\u3002\u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u521d\u59cb\u503c\u3002<\/p>\n
\u4f7f\u7528\u573a\u666f 1\uff1a\u6c42\u548c<\/h3>\n
\u521d\u59cb\u503c 0\uff0c\u56de\u8c03\u91cc\u6253\u5370\u7684 sum2 \u4f9d\u6b21\u662f 0\u300110\u300130\uff0c\u6700\u540e sumValue \u4e3a 60\u3002<\/p>\n
var numbers = [10,20,30];\n\n var sum = 0;\n\n\/\/es5 \u65b9\u6cd5\n\nfor(var i = 0; i < numbers.length; i++){\n\n  sum += numbers[i];\n\n}\n\nconsole.log(sum);\n\n\/\/ es6 reduce\n\nvar sumValue = numbers.reduce(function(sum2,number2){\n\n  console.log(sum2);\/\/0 10 30 60\n\n  return sum2 + number2;\n\n},0);\/\/sum2\u521d\u59cb\u503c\u4e3a0\n\nconsole.log(sumValue);<\/code><\/pre>\n
\u4f7f\u7528\u573a\u666f 2\uff1a\u62bd\u51fa\u5c5e\u6027\u5230\u65b0\u6570\u7ec4<\/h3>\n
var primaryColors = [\n\n   {color:\"red\"},\n\n   {color:\"yellow\"},\n\n   {color:\"blue\"}\n\n ];\n\n var colors = primaryColors.reduce(function(previous,primaryColor){\n\n    previous.push(primaryColor.color);\n\n    return previous;\n\n },[]);\n\n console.log(colors);\/\/[\"red\", \"yellow\", \"blue\"]<\/code><\/pre>\n
\u4f7f\u7528\u573a\u666f 3\uff1a\u62ec\u53f7\u662f\u5426\u5bf9\u79f0<\/h3>\n
\u9047\u5230 (<\/code> \u52a0\u4e00\uff0c\u9047\u5230 )<\/code> \u51cf\u4e00\uff1b\u4e2d\u9014\u5c0f\u4e8e 0 \u6216\u6700\u7ec8\u4e0d\u662f 0 \u90fd\u4e0d\u5bf9\u79f0\u3002balancedParens(\"((())))\")<\/code> \u591a\u4e86\u4e00\u4e2a\u53f3\u62ec\u53f7\uff0c\u7ed3\u679c\u4e3a false\u3002<\/p>\n
function balancedParens(string){\n\n  return !string.split(\"\").reduce(function(previous,char){\n\n    if(previous < 0) { return previous;}\n\n    if(char == \"(\"){ return ++previous;}\n\n    if(char == \")\"){ return --previous;}\n\n    return previous;\n\n  },0);\n\n}\n\nconsole.log(balancedParens(\"((())))\"));<\/code><\/pre>\n\n\n\n\n\n\n\n\n\n\n\n
\u65b9\u6cd5<\/th>\n\u8fd4\u56de\u503c<\/th>\n\u505c\u4e0d\u505c<\/th>\n\u5178\u578b\u7528\u9014<\/th>\n<\/tr>\n<\/thead>\n
forEach<\/code><\/td>\nundefined<\/td>\n\u4e0d\u56e0 return \u505c\u904d\u5386<\/td>\n\u526f\u4f5c\u7528\uff1a\u6253\u5370\u3001\u7d2f\u52a0\u5916\u90e8\u53d8\u91cf<\/td>\n<\/tr>\n
map<\/code><\/td>\n\u7b49\u957f\u65b0\u6570\u7ec4<\/td>\n\u8dd1\u5b8c\u5168\u8868<\/td>\n\u6620\u5c04\u3001\u62bd\u5b57\u6bb5<\/td>\n<\/tr>\n
filter<\/code><\/td>\n\u5b50\u96c6\u65b0\u6570\u7ec4<\/td>\n\u8dd1\u5b8c\u5168\u8868<\/td>\n\u7b5b\u9009<\/td>\n<\/tr>\n
find<\/code><\/td>\n\u7b2c\u4e00\u4e2a\u5143\u7d20\u6216 undefined<\/td>\n\u627e\u5230\u5373\u505c<\/td>\n\u67e5\u4e00\u6761<\/td>\n<\/tr>\n
every<\/code><\/td>\nboolean<\/td>\n\u9047\u5230\u5047\u5373\u505c<\/td>\n\u5168\u90e8\u5408\u683c\uff1f<\/td>\n<\/tr>\n
some<\/code><\/td>\nboolean<\/td>\n\u9047\u5230\u771f\u5373\u505c<\/td>\n\u662f\u5426\u5b58\u5728\uff1f<\/td>\n<\/tr>\n
reduce<\/code><\/td>\n\u7d2f\u8ba1\u7ed3\u679c<\/td>\n\u8dd1\u5b8c\u5168\u8868<\/td>\n\u6c42\u548c\u3001\u6298\u53e0\u3001\u5224\u62ec\u53f7<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n
\u4e00\u53e5\u8bdd\u603b\u7ed3\uff1a\u904d\u5386\u7528 forEach\uff0c\u53d8\u5f62\u7528 map\uff0c\u7b5b\u9009\u7528 filter\uff0c\u627e\u4e00\u6761\u7528 find\uff0c\u5168\u771f\/\u6709\u771f\u7528 every\/some\uff0c\u6298\u53e0\u6210\u4e00\u4e2a\u503c\u7528 reduce\u3002<\/strong><\/p>\n<\/blockquote>\n<\/section>\n","protected":false},"excerpt":{"rendered":"
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