bi\u1ebfn trong JavaScript<\/a>.<\/p>\n\n\n\nD\u1ea5u ngo\u1eb7c \u0111\u01a1n c\u00f3 th\u1ec3 bao g\u1ed3m c\u00e1c tham s\u1ed1 \u0111\u01b0\u1ee3c ph\u00e2n c\u00e1ch b\u1edfi d\u1ea5u ph\u1ea9y:<\/p>\n\n\n\n
(tham s\u1ed1 1, tham s\u1ed1 2, ...)<\/code><\/pre>\n\n\n\nC\u00e1c \u0111o\u1ea1n code \u0111\u01b0\u1ee3c th\u1ef1c thi b\u1edfi h\u00e0m s\u1ebd \u0111\u01b0\u1ee3c \u0111\u01b0a v\u00e0o b\u00ean trong ngo\u1eb7c nh\u1ecdn: <\/p>\n\n\n\n
{}<\/code><\/pre>\n\n\n\nC\u00fa ph\u00e1p chung gi\u1ed1ng nh\u01b0 th\u1ebf n\u00e0y:<\/p>\n\n\n\n
function t\u00ean_h\u00e0m (tham s\u1ed1 1, tham s\u1ed1 2, tham s\u1ed1 3) {code th\u1ef1c thi}<\/code><\/pre>\n\n\n\nTham s\u1ed1<\/strong> (parameters) c\u1ee7a h\u00e0m l\u00e0 c\u00e1c t\u00ean \u0111\u01b0\u1ee3c li\u1ec7t k\u00ea trong \u0111\u1ecbnh ngh\u0129a h\u00e0m, \u1edf trong d\u1ea5u ngo\u1eb7c \u0111\u01a1n.<\/p>\n\n\n\n\u0110\u1ed1i s\u1ed1<\/strong> (arguments) c\u1ee7a h\u00e0m l\u00e0 c\u00e1c gi\u00e1 tr\u1ecb th\u1ef1c nh\u1eadn \u0111\u01b0\u1ee3c khi h\u00e0m \u0111\u01b0\u1ee3c g\u1ecdi.<\/p>\n\n\n\nB\u00ean trong h\u00e0m, c\u00e1c \u0111\u1ed1i s\u1ed1 \u0111\u01b0\u1ee3c c\u01b0 x\u1eed nh\u01b0 c\u00e1c bi\u1ebfn \u0111\u1ecba ph\u01b0\u01a1ng.<\/p>\n\n\n\n
M\u1ed9t h\u00e0m c\u0169ng t\u01b0\u01a1ng t\u1ef1 Th\u1ee7 t\u1ee5c (procedure) ho\u1eb7c Ch\u01b0\u01a1ng tr\u00ecnh con (subroutine) trong c\u00e1c ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh kh\u00e1c.<\/p>\n\n\n\n
\u0110\u1ebfn ph\u1ea7n n\u00e0y, b\u1ea1n n\u00e0o t\u1eebng h\u1ecdc PHP c\u00f3 th\u1ec3 th\u1ea5y c\u1ea5u tr\u00fac h\u00e0m, c\u00e1ch vi\u1ebft c\u1ee7a JS r\u1ea5t gi\u1ed1ng v\u1edbi PHP.<\/p>\n\n\n\n
\n\n\n\n<\/span>G\u1ecdi h\u00e0m<\/span><\/h2>\n\n\n\n\u0110o\u1ea1n code b\u00ean trong h\u00e0m s\u1ebd \u0111\u01b0\u1ee3c th\u1ef1c thi khi “c\u00e1i g\u00ec \u0111\u00f3” g\u1ecdi h\u00e0m:<\/p>\n\n\n\n
Khi m\u1ed9t s\u1ef1 ki\u1ec7n xu\u1ea5t hi\u1ec7n (ch\u1eb3ng h\u1ea1n khi ng\u01b0\u1eddi d\u00f9ng click v\u00e0o n\u00fat);<\/li> Khi n\u00f3 \u0111\u01b0\u1ee3c g\u1ecdi t\u1eeb m\u00e3 JavaScript;<\/li> T\u1ef1 \u0111\u1ed9ng (t\u1ef1 g\u1ecdi h\u00e0m);<\/li><\/ul>\n\n\n\n \n\n\n\n<\/span>K\u1ebft qu\u1ea3 tr\u1ea3 v\u1ec1 trong H\u00e0m<\/span><\/h2>\n\n\n\nKhi JavaScript \u0111i \u0111\u1ebfn l\u1ec7nh return<\/code><\/strong>, h\u00e0m s\u1ebd ng\u1eebng kh\u00f4ng th\u1ef1c thi n\u1eefa.<\/p>\n\n\n\nN\u1ebfu h\u00e0m \u0111\u01b0\u1ee3c g\u1ecdi t\u1eeb m\u1ed9t l\u1ec7nh, JavaScript s\u1ebd “return” \u0111\u1ec3 th\u1ef1c thi code sau c\u00e2u l\u1ec7nh g\u1ecdi.<\/p>\n\n\n\n
C\u00e1c h\u00e0m th\u01b0\u1eddng t\u00ednh to\u00e1n gi\u00e1 tr\u1ecb tr\u1ea3 v\u1ec1<\/strong> (return value). Gi\u00e1 tr\u1ecb tr\u1ea3 v\u1ec1 l\u00e0 “tr\u1ea3 l\u1ea1i \/ returned” tr\u1edf l\u1ea1i v\u1edbi “ng\u01b0\u1eddi g\u1ecdi \/ caller”:<\/p>\n\n\n\nV\u00ed d\u1ee5:<\/p>\n\n\n\n
T\u00ecnh to\u00e1n ph\u00e9p t\u00ednh t\u1eeb hai s\u1ed1 sau v\u00e0 tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3:<\/p>\n\n\n\n
var x = myFunction(4, 3); \/\/ H\u00e0m \u0111\u01b0\u1ee3c g\u1ecdi, gi\u00e1 tr\u1ecb tr\u1ea3 v\u1ec1 cu\u1ed1i c\u00f9ng \u0111\u01b0\u1ee3c g\u00e1n cho x\n\nfunction myFunction(a, b) {\n return a * b;\/\/ H\u00e0m tr\u1ea3 v\u1ec1 gi\u00e1 tr\u1ecb c\u1ee7a ph\u00e9p nh\u00e2n a v\u00e0 b\n}<\/code><\/pre>\n\n\n\nK\u1ebft qu\u1ea3 c\u1ee7a x v\u00ec v\u1eady s\u1ebd l\u00e0:<\/p>\n\n\n\n
12<\/code><\/pre>\n\n\n\n \n\n\n\n<\/span>T\u1ea1i sao d\u00f9ng h\u00e0m?<\/span><\/h2>\n\n\n\nB\u1ea1n c\u00f3 th\u1ec3 d\u00f9ng l\u1ea1i m\u00e3 \u0111\u00e3 th\u1ef1c hi\u1ec7n: Thao t\u00e1c code m\u1ed9t l\u1ea7n, v\u00e0 s\u1eed d\u1ee5ng n\u00f3 b\u1ea5t c\u1ee9 khi n\u00e0o b\u1ea1n mu\u1ed1n.<\/p>\n\n\n\n
B\u1ea1n c\u00f3 th\u1ec3 d\u00f9ng c\u00f9ng m\u1ed9t code nhi\u1ec1u l\u1ea7n v\u1edbi c\u00e1c \u0111\u1ed1i s\u1ed1 kh\u00e1c nhau \u0111\u1ec3 t\u1ea1o ra c\u00e1c k\u1ebft qu\u1ea3 kh\u00e1c nhau.<\/p>\n\n\n\n
V\u00ed d\u1ee5:<\/p>\n\n\n\n
Chuy\u1ec3n \u0111\u1ed5i nhi\u1ec7t \u0111\u1ed9 F sang \u0111\u1ed9 C:<\/p>\n\n\n\n
function toCelsius(fahrenheit) {\n return (5\/9) * (fahrenheit-32);\n}\n\ndocument.getElementById(\"demo\").innerHTML = toCelsius(77);<\/code><\/pre>\n\n\n\n \n\n\n\n<\/span>To\u00e1n t\u1eed () g\u1ecdi h\u00e0m<\/span><\/h2>\n\n\n\nS\u1eed d\u1ee5ng v\u00ed d\u1ee5 \u1edf tr\u00ean, toCelsius<\/code> \u0111\u1ec1 c\u1eadp \u0111\u1ebfn \u0111\u1ed1i t\u01b0\u1ee3ng h\u00e0m<\/strong> (function object), v\u00e0 toCelsius()<\/code> \u0111\u1ec1 c\u1eadp \u0111\u1ebfn k\u1ebft qu\u1ea3 c\u1ee7a h\u00e0m<\/strong> (function result).<\/p>\n\n\n\nV\u00ed d\u1ee5:<\/p>\n\n\n\n
Truy c\u1eadp m\u1ed9t h\u00e0m kh\u00f4ng c\u00f3 () s\u1ebd tr\u1ea3 v\u1ec1 \u0111\u1ecbnh ngh\u0129a c\u1ee7a h\u00e0m<\/strong> ch\u1ee9 kh\u00f4ng ph\u1ea3i k\u1ebft qu\u1ea3:<\/p>\n\n\n\nfunction toCelsius(fahrenheit) {\n return (5\/9) * (fahrenheit-32);\n}\n document.getElementById(\"demo\").innerHTML = toCelsius;<\/code><\/pre>\n\n\n\n \n\n\n\n<\/span>S\u1eed d\u1ee5ng h\u00e0m nh\u01b0 l\u00e0 bi\u1ebfn<\/span><\/h2>\n\n\n\nC\u00e1c h\u00e0m c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c d\u00f9ng nh\u01b0 c\u00e1c bi\u1ebfn trong c\u00e1c c\u00f4ng th\u1ee9c, b\u00e0i t\u1eadp v\u00e0 t\u00ednh to\u00e1n.<\/p>\n\n\n\n
V\u00ed d\u1ee5:<\/p>\n\n\n\n
B\u1ea1n c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng:<\/p>\n\n\n\n
let text = \"Nhi\u1ec7t \u0111\u1ed9 l\u00e0 \" + toCelsius(77) + \" \u0111\u1ed9 C\";<\/code><\/pre>\n\n\n\nThay cho:<\/p>\n\n\n\n
let x = toCelsius(77);\nlet text = \"Nhi\u1ec7t \u0111\u1ed9 l\u00e0 \" + x + \" \u0111\u1ed9 C\";<\/code><\/pre>\n\n\n\nB\u1ea1n c\u00f3 th\u1ec3 th\u1ea5y l\u00e0 nh\u1edd coi h\u00e0m nh\u01b0 l\u00e0 bi\u1ebfn, b\u1ea1n \u0111\u1ee1 \u0111\u01b0\u1ee3c m\u1ed9t thao t\u00e1c g\u00e1n. Tuy nhi\u00ean kh\u00f4ng ph\u1ea3i l\u00fac n\u00e0o l\u00e0m th\u1ebf c\u0169ng hay, \u0111\u00f4i khi ch\u00fang ta mu\u1ed1n m\u00e3 d\u1ec5 nh\u00ecn, r\u00f5 r\u00e0ng h\u01a1n th\u00ec vi\u1ec7c g\u00e1n bi\u1ebfn v\u00e0o h\u00e0m, r\u1ed3i thao t\u00e1c v\u1edbi bi\u1ebfn \u0111\u00f3 c\u0169ng kh\u00f4ng ph\u1ea3i l\u00e0 \u00fd t\u01b0\u1edfng t\u1ec7.<\/p>\n\n\n\n
<\/span>Bi\u1ebfn c\u1ee5c b\u1ed9<\/span><\/h2>\n\n\n\nBi\u1ebfn \u0111\u01b0\u1ee3c khai b\u00e1o trong h\u00e0m l\u00e0 bi\u1ebfn c\u1ee5c b\u1ed9 (LOCAL), bi\u1ebfn c\u1ee5c b\u1ed9 ch\u1ec9 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c truy c\u1eadp t\u1eeb b\u00ean trong h\u00e0m m\u00e0 th\u00f4i.<\/p>\n\n\n\n
V\u00ed d\u1ee5:<\/p>\n\n\n\n
\/\/ m\u00e3 \u1edf \u0111\u00e2y KH\u00d4NG th\u1ec3 s\u1eed d\u1ee5ng bi\u1ebfn carName \u0111\u1ec3 thao t\u00e1c\n\nfunction myFunction() {\n let carName = \"Volvo\";\n \/\/ m\u00e3 \u1edf \u0111\u00e2y n\u1ebfu mu\u1ed1n c\u00f3 kh\u1ea3 n\u0103ng d\u00f9ng bi\u1ebfn carName \u0111\u1ec3 thao t\u00e1c\n}\n\n\/\/ m\u00e3 \u1edf \u0111\u00e2y KH\u00d4NG th\u1ec3 s\u1eed d\u1ee5ng bi\u1ebfn carName \u0111\u1ec3 thao t\u00e1c<\/code><\/pre>\n\n\n\nQuy t\u1eafc bi\u1ebfn c\u1ee5c b\u1ed9 trong h\u00e0m c\u1ee7a JS c\u0169ng r\u1ea5t gi\u1ed1ng v\u1edbi quy t\u1eafc c\u1ee7a PHP.<\/p>\n\n\n\n
V\u00ec c\u00e1c bi\u1ebfn c\u1ee5c b\u1ed9 ch\u1ec9 \u0111\u01b0\u1ee3c ghi nh\u1eadn \u1edf b\u00ean trong h\u00e0m, c\u00e1c bi\u1ebfn c\u00f9ng t\u00ean c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong c\u00e1c h\u00e0m kh\u00e1c nhau.<\/p>\n\n\n\n
Bi\u1ebfn c\u1ee5c b\u1ed9 \u0111\u01b0\u1ee3c t\u1ea1o khi h\u00e0m b\u1eaft \u0111\u1ea7u, v\u00e0 s\u1ebd b\u1ecb x\u00f3a khi h\u00e0m ho\u00e0n th\u00e0nh xong nhi\u1ec7m v\u1ee5.<\/p>\n","protected":false},"excerpt":{"rendered":"
H\u00e0m trong JS c\u0169ng gi\u1ed1ng nh\u01b0 h\u00e0m trong PHP gi\u00fap ch\u00fang ta x\u00e2y d\u1ef1ng m\u1ed9t nhi\u1ec7m v\u1ee5 m\u00e0 ph\u1ea3i th\u01b0\u1eddng xuy\u00ean d\u00f9ng l\u1ea1i ho\u1eb7c khi n\u00f3 r\u1ea5t ph\u1ee9c t\u1ea1p ch\u00fang ta mu\u1ed1n t\u1ea1o v\u00e0 t\u00e1ch n\u00f3 r\u1ed3i \u0111\u1ec3 \u1edf m\u1ed9t file ri\u00eang v\u00e0 ch\u1ec9 g\u1ecdi \u0111\u1ebfn khi c\u1ea7n. K\u1ef9 n\u0103ng vi\u1ebft h\u00e0m r\u1ea5t quan tr\u1ecdng, …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[236],"tags":[],"yoast_head":"\n
C\u00e1c h\u00e0m (function) trong JavaScript • Ki\u1ebfn c\u00e0ng<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n","yoast_head_json":{"title":"C\u00e1c h\u00e0m (function) trong JavaScript • Ki\u1ebfn c\u00e0ng","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/kiencang.net\/cac-ham-trong-javascript\/","og_locale":"vi_VN","og_type":"article","og_title":"C\u00e1c h\u00e0m (function) trong JavaScript • Ki\u1ebfn c\u00e0ng","og_description":"H\u00e0m trong JS c\u0169ng gi\u1ed1ng nh\u01b0 h\u00e0m trong PHP gi\u00fap ch\u00fang ta x\u00e2y d\u1ef1ng m\u1ed9t nhi\u1ec7m v\u1ee5 m\u00e0 ph\u1ea3i th\u01b0\u1eddng xuy\u00ean d\u00f9ng l\u1ea1i ho\u1eb7c khi n\u00f3 r\u1ea5t ph\u1ee9c t\u1ea1p ch\u00fang ta mu\u1ed1n t\u1ea1o v\u00e0 t\u00e1ch n\u00f3 r\u1ed3i \u0111\u1ec3 \u1edf m\u1ed9t file ri\u00eang v\u00e0 ch\u1ec9 g\u1ecdi \u0111\u1ebfn khi c\u1ea7n. K\u1ef9 n\u0103ng vi\u1ebft h\u00e0m r\u1ea5t quan tr\u1ecdng, …","og_url":"https:\/\/kiencang.net\/cac-ham-trong-javascript\/","og_site_name":"Ki\u1ebfn c\u00e0ng","article_author":"https:\/\/www.facebook.com\/anhducnguyen87\/","article_published_time":"2016-07-05T03:22:12+00:00","author":"Nguy\u1ec5n \u0110\u1ee9c Anh","twitter_card":"summary_large_image","twitter_misc":{"\u0110\u01b0\u1ee3c vi\u1ebft b\u1edfi":"Nguy\u1ec5n \u0110\u1ee9c Anh","\u01af\u1edbc t\u00ednh th\u1eddi gian \u0111\u1ecdc":"4 ph\u00fat"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/kiencang.net\/cac-ham-trong-javascript\/","url":"https:\/\/kiencang.net\/cac-ham-trong-javascript\/","name":"C\u00e1c h\u00e0m (function) trong JavaScript • Ki\u1ebfn c\u00e0ng","isPartOf":{"@id":"https:\/\/kiencang.net\/#website"},"datePublished":"2016-07-05T03:22:12+00:00","dateModified":"2016-07-05T03:22:12+00:00","author":{"@id":"https:\/\/kiencang.net\/#\/schema\/person\/5e7e1a04d8d1218ad8c421ba43d25c16"},"breadcrumb":{"@id":"https:\/\/kiencang.net\/cac-ham-trong-javascript\/#breadcrumb"},"inLanguage":"vi","potentialAction":[{"@type":"ReadAction","target":["https:\/\/kiencang.net\/cac-ham-trong-javascript\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/kiencang.net\/cac-ham-trong-javascript\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/kiencang.net\/"},{"@type":"ListItem","position":2,"name":"C\u00e1c h\u00e0m (function) trong JavaScript"}]},{"@type":"WebSite","@id":"https:\/\/kiencang.net\/#website","url":"https:\/\/kiencang.net\/","name":"Ki\u1ebfn c\u00e0ng","description":"\u00d4m l\u00fd thuy\u1ebft, h\u00f4n th\u1ef1c h\u00e0nh","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/kiencang.net\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"vi"},{"@type":"Person","@id":"https:\/\/kiencang.net\/#\/schema\/person\/5e7e1a04d8d1218ad8c421ba43d25c16","name":"Nguy\u1ec5n \u0110\u1ee9c Anh","image":{"@type":"ImageObject","inLanguage":"vi","@id":"https:\/\/kiencang.net\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/6d71f9b89393952a8382e30dad26c1ec?s=96&d=monsterid&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/6d71f9b89393952a8382e30dad26c1ec?s=96&d=monsterid&r=g","caption":"Nguy\u1ec5n \u0110\u1ee9c Anh"},"description":"Sinh n\u0103m 1987, t\u1ed1t nghi\u1ec7p Cao \u0111\u1eb3ng th\u1ef1c h\u00e0nh FPT qu\u00e3ng 2014, chuy\u00ean ng\u00e0nh Thi\u1ebft k\u1ebf website. 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