<\/span><\/h2>\n\n\n\nM\u1ea3ng l\u00e0 m\u1ed9t bi\u1ebfn \u0111\u1eb7c bi\u1ec7t, c\u00f3 th\u1ec3 ch\u1ee9a h\u01a1n m\u1ed9t gi\u00e1 tr\u1ecb v\u00e0o m\u1ed9t th\u1eddi \u0111i\u1ec3m.<\/p>\n\n\n\n
N\u1ebfu b\u1ea1n c\u00f3 m\u1ed9t danh m\u1ee5c s\u1ea3n ph\u1ea9m (v\u00ed d\u1ee5 nh\u01b0 danh s\u00e1ch t\u00ean \u00f4 t\u00f4), b\u1ea1n c\u00f3 th\u1ec3 l\u01b0u gi\u1eef t\u1eebng lo\u1ea1i trong m\u1ed9t danh s\u00e1ch c\u00e1c bi\u1ebfn \u0111\u01a1n gi\u1ed1ng nh\u01b0 th\u1ebf n\u00e0y:<\/p>\n\n\n\n
var car1 = \"Saab\";\nvar car2 = \"Volvo\";\nvar car3 = \"BMW\";<\/code><\/pre>\n\n\n\nTuy nhi\u00ean n\u1ebfu b\u1ea1n c\u1ea7n m\u1ed9t v\u00f2ng l\u1eb7p qua c\u00e1c lo\u1ea1i \u00f4 t\u00f4 v\u00e0 c\u1ea7n t\u00ecm ki\u1ebfm m\u1ed9t lo\u1ea1i n\u00e0o \u0111\u00f3? V\u00e0 n\u1ebfu kh\u00f4ng ph\u1ea3i b\u1ea1n c\u00f3 3 \u00f4 t\u00f4 m\u00e0 l\u00e0 300 th\u00ec l\u00e0m th\u1ebf n\u00e0o?<\/p>\n\n\n\n
Gi\u1ea3i ph\u00e1p l\u00e0 d\u00f9ng m\u1ea3ng!<\/p>\n\n\n\n
M\u1ed9t m\u1ea3ng c\u00f3 th\u1ec3 n\u1eafm gi\u1eef nhi\u1ec1u gi\u00e1 tr\u1ecb trong m\u1ed9t bi\u1ebfn duy nh\u1ea5t, v\u00e0 b\u1ea1n c\u00f3 th\u1ec3 truy c\u1eadp gi\u00e1 tr\u1ecb b\u1eb1ng c\u00e1ch li\u00ean k\u1ebft v\u1edbi ch\u1ec9 s\u1ed1.<\/p>\n\n\n\n
\n\n\n\n<\/span>T\u1ea1o m\u1ea3ng<\/span><\/h2>\n\n\n\nC\u00e1ch d\u1ec5 nh\u1ea5t \u0111\u1ec3 khai b\u00e1o m\u1ea3ng gi\u1ed1ng nh\u01b0 d\u01b0\u1edbi \u0111\u00e2y.<\/p>\n\n\n\n
C\u00fa ph\u00e1p:<\/p>\n\n\n\n
var array-name = [item1, item2, ...];<\/code><\/pre>\n\n\n\n
\n\n\n\nV\u00ed d\u1ee5<\/p>\n\n\n\n
var cars = [\"Saab\", \"Volvo\", \"BMW\"];<\/code><\/pre>\n\n\n\nKho\u1ea3ng tr\u1ed1ng v\u00e0 xu\u1ed1ng d\u00f2ng kh\u00f4ng quan tr\u1ecdng. M\u1ed9t khai b\u00e1o c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c chia ra tr\u00ean nhi\u1ec1u d\u00f2ng:<\/p>\n\n\n\n
\n\n\n\nV\u00ed d\u1ee5<\/p>\n\n\n\n
var cars = [\n \"Saab\",\n \"Volvo\",\n \"BMW\"\n ];<\/code><\/pre>\n\n\n\nKh\u00f4ng bao gi\u1edd th\u00eam d\u1ea5u ph\u1ea9y \u0111\u1eb1ng sau ph\u1ea7n t\u1eed cu\u1ed1i c\u00f9ng (v\u00ed d\u1ee5 “BMW”,). \u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 t\u1ea1o ra c\u00e1c hi\u1ec7u \u1ee9ng kh\u00f4ng t\u1ed1t tr\u00ean c\u00e1c tr\u00ecnh duy\u1ec7t.<\/p>\n\n\n\n
\n\n\n\n<\/span>S\u1eed d\u1ee5ng t\u1eeb kho\u00e1 new trong JavaScript<\/span><\/h2>\n\n\n\nV\u00ed d\u1ee5 d\u01b0\u1edbi \u0111\u00e2y c\u0169ng d\u00f9ng \u0111\u1ec3 t\u1ea1o M\u1ea3ng v\u00e0 g\u00e1n gi\u00e1 tr\u1ecb cho n\u00f3:<\/p>\n\n\n\n
V\u00ed d\u1ee5<\/h3>\n\n\n\nvar cars = new Array(\"Saab\", \"Volvo\", \"BMW\");<\/code><\/pre>\n\n\n\nHai v\u00ed d\u1ee5 tr\u00ean ho\u00e0n to\u00e0n gi\u1ed1ng nhau v\u1ec1 m\u1eb7t gi\u00e1 tr\u1ecb. Th\u1ef1c ra b\u1ea1n kh\u00f4ng c\u1ea7n s\u1eed d\u1ee5ng new Array() \u0111\u1ec3 t\u1ea1o m\u1ea3ng.<\/p>\n\n\n\n
\u0110\u1ec3 cho v\u1ea5n \u0111\u1ec1 tr\u1edf n\u00ean \u0111\u01a1n gi\u1ea3n, d\u1ec5 \u0111\u1ecdc v\u00e0 t\u0103ng t\u1ed1c \u0111\u1ed9 x\u1eed l\u00fd, b\u1ea1n h\u00e3y s\u1eed d\u1ee5ng c\u00e1ch \u0111\u1ea7u ti\u00ean nh\u00e9, c\u00e1ch m\u00e0 kh\u00f4ng c\u1ea7n d\u00f9ng \u0111\u1ebfn t\u1eeb kho\u00e1 new \u00ed.<\/p>\n\n\n\n
\n\n\n\n<\/span>Truy c\u1eadp c\u00e1c ph\u1ea7n t\u1eed c\u1ee7a M\u1ea3ng<\/span><\/h2>\n\n\n\nB\u1ea1n truy c\u1eadp c\u00e1c ph\u1ea7n t\u1eed c\u1ee7a m\u1ea3ng th\u00f4ng qua li\u00ean k\u1ebft t\u1edbi c\u00e1c ch\u1ec9 s\u1ed1<\/strong>.<\/p>\n\n\n\nC\u00e2u l\u1ec7nh d\u01b0\u1edbi \u0111\u00e2y truy c\u1eadp gi\u00e1 tr\u1ecb c\u1ee7a ph\u1ea7n t\u1eed \u0111\u1ea7u ti\u00ean trong cars:<\/p>\n\n\n\n
var name = cars[0];<\/code><\/pre>\n\n\n\nC\u00e2u l\u1ec7nh ti\u1ebfp theo ch\u1ec9nh s\u1eeda ph\u1ea7n t\u1eed \u0111\u1ea7u ti\u00ean trong cars:<\/p>\n\n\n\n
cars[0] = \"Opel\";<\/code><\/pre>\n\n\n\nV\u00ed d\u1ee5<\/h3>\n\n\n\nvar cars = [\"Saab\", \"Volvo\", \"BMW\"];\ndocument.getElementById(\"demo\").innerHTML = cars[0];<\/code><\/pre>\n\n\n\n[0] l\u00e0 ph\u1ea7n t\u1eed \u0111\u1ea7u ti\u00ean trong m\u1ea3ng. [1] l\u00e0 ph\u1ea7n t\u1eed th\u1ee9 hai. Ch\u1ec9 s\u1ed1 m\u1ea3ng b\u1eaft \u0111\u1ea7u t\u1eeb 0.<\/p>\n\n\n\n
\n\n\n\n<\/span>Truy c\u1eadp t\u1ea5t c\u1ea3 M\u1ea3ng<\/span><\/h2>\n\n\n\nV\u1edbi JavaScript, t\u1ea5t c\u1ea3 m\u1ea3ng c\u00f3 th\u1ec3 truy c\u1eadp b\u1eb1ng c\u00e1ch li\u00ean k\u1ebft v\u1edbi t\u00ean m\u1ea3ng:<\/p>\n\n\n\n
V\u00ed d\u1ee5<\/h3>\n\n\n\nvar cars = [\"Saab\", \"Volvo\", \"BMW\"];\ndocument.getElementById(\"demo\").innerHTML = cars;<\/code><\/pre>\n\n\n\n
\n\n\n\n<\/span>M\u1ea3ng nh\u01b0 l\u00e0 \u0110\u1ed1i t\u01b0\u1ee3ng<\/span><\/h2>\n\n\n\nM\u1ea3ng l\u00e0 d\u1ea1ng \u0111\u1eb7c bi\u1ec7t c\u1ee7a \u0111\u1ed1i t\u01b0\u1ee3ng. Khi b\u1ea1n s\u1eed d\u1ee5ng to\u00e1n t\u1eed typeof <\/strong>trong JavaScript, b\u1ea1n s\u1ebd nh\u1eadn \u0111\u01b0\u1ee3c k\u1ebft qu\u1ea3 tr\u1ea3 v\u1ec1 l\u00e0 “object” – \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n\n\n\nNh\u01b0ng, c\u00e1c m\u1ea3ng trong JavaScript \u0111\u01b0\u1ee3c m\u00f4 t\u1ea3 t\u1ed1t nh\u1ea5t nh\u01b0 m\u1ea3ng.<\/p>\n\n\n\n
M\u1ea3ng s\u1eed d\u1ee5ng ch\u1ec9 s\u1ed1 \u0111\u1ec3 truy c\u1eadp v\u00e0o c\u00e1c ph\u1ea7n t\u1eed<\/strong> c\u1ee7a n\u00f3. Trong v\u00ed d\u1ee5 d\u01b0\u1edbi \u0111\u00e2y, person[0]<\/strong> tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 \u0110\u1ee9c Anh:<\/p>\n\n\n\nM\u1ea3ng:<\/h3>\n\n\n\nvar person = [\"\u0110\u1ee9c Anh\", \"Nguy\u1ec5n\", 30];<\/code><\/pre>\n\n\n\n\u0110\u1ed1i t\u01b0\u1ee3ng s\u1eed d\u1ee5ng t\u00ean (names) <\/strong>\u0111\u1ec3 truy c\u1eadp c\u00e1c “th\u00e0nh vi\u00ean” c\u1ee7a n\u00f3. Trong v\u00ed d\u1ee5 n\u00e0y person.firstName <\/strong>tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 \u0110\u1ee9c Anh:<\/p>\n\n\n\n\u0110\u1ed1i t\u01b0\u1ee3ng:<\/h3>\n\n\n\nvar person = {firstName:\"\u0110\u1ee9c Anh\", lastName:\"Nguy\u1ec5n\", age:30};<\/code><\/pre>\n\n\n\n
\n\n\n\n<\/span>Ph\u1ea7n t\u1eed m\u1ea3ng c\u00f3 th\u1ec3 l\u00e0 \u0110\u1ed1i t\u01b0\u1ee3ng<\/span><\/h2>\n\n\n\nBi\u1ebfn trong JavaScript c\u00f3 th\u1ec3 l\u00e0 \u0111\u1ed1i t\u01b0\u1ee3ng. M\u1ea3ng l\u00e0 d\u1ea1ng \u0111\u1eb7c bi\u1ec7t c\u1ee7a \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n\n\n\n
V\u00ec l\u00fd do \u0111\u00f3, b\u1ea1n c\u00f3 th\u1ec3 c\u00f3 c\u00e1c ki\u1ec3u kh\u00e1c nhau c\u1ee7a bi\u1ebfn trong c\u00f9ng m\u1ed9t M\u1ea3ng.<\/p>\n\n\n\n
B\u1ea1n c\u00f3 th\u1ec3 c\u00f3 c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng trong M\u1ea3ng. B\u1ea1n c\u00f3 th\u1ec3 c\u00f3 c\u00e1c h\u00e0m trong M\u1ea3ng. B\u1ea1n c\u00f3 th\u1ec3 c\u00f3 m\u1ea3ng trong M\u1ea3ng:<\/p>\n\n\n\n
myArray[0] = Date.now;\nmyArray[1] = myFunction;\nmyArray[2] = myCars;<\/code><\/pre>\n\n\n\n
\n\n\n\n<\/span>C\u00e1c thu\u1ed9c t\u00ednh v\u00e0 ph\u01b0\u01a1ng th\u1ee9c c\u1ee7a M\u1ea3ng<\/span><\/h2>\n\n\n\nS\u1ee9c m\u1ea1nh th\u1ef1c s\u1ef1 c\u1ee7a m\u1ea3ng trong JavaScript l\u00e0 c\u00e1c thu\u1ed9c t\u00ednh v\u00e0 ph\u01b0\u01a1ng th\u1ee9c \u0111\u01b0\u1ee3c x\u00e2y d\u1ef1ng b\u00ean trong n\u00f3:<\/p>\n\n\n\n
V\u00ed d\u1ee5<\/h3>\n\n\n\nvar x = cars.length; \/\/ Thu\u1ed9c t\u00ednh length tr\u1ea3 v\u1ec1 s\u1ed1 l\u01b0\u1ee3ng ph\u1ea7n t\u1eed \nvar y = cars.sort(); \/\/ Ph\u01b0\u01a1ng th\u1ee9c sort() s\u1eafp x\u1ebfp m\u1ea3ng <\/code><\/pre>\n\n\n\n
\n\n\n\n<\/span>Thu\u1ed9c t\u00ednh length<\/span><\/h2>\n\n\n\nThu\u1ed9c t\u00ednh length <\/strong>c\u1ee7a m\u1ea3ng tr\u1ea3 v\u1ec1 \u0111\u1ed9 d\u00e0i c\u1ee7a m\u1ea3ng (s\u1ed1 l\u01b0\u1ee3ng c\u1ee7a ph\u1ea7n t\u1eed m\u1ea3ng).<\/p>\n\n\n\nV\u00ed d\u1ee5<\/h3>\n\n\n\nvar fruits = [\"Banana\", \"Orange\", \"Apple\", \"Mango\"];\nfruits.length; \/\/ \u0111\u1ed9 d\u00e0i c\u1ee7a m\u1ea3ng l\u00e0 4<\/code><\/pre>\n\n\n\n\u0110\u1ed9 d\u00e0i c\u1ee7a m\u1ea3ng bao gi\u1edd c\u0169ng h\u01a1n ch\u1ec9 s\u1ed1 l\u1edbn nh\u1ea5t trong m\u1ea3ng m\u1ed9t \u0111\u01a1n v\u1ecb.<\/p>\n\n\n\n
\n\n\n\n<\/span>Th\u00eam m\u1ed9t ph\u1ea7n t\u1eed trong m\u1ea3ng<\/span><\/h2>\n\n\n\nC\u00e1ch d\u1ec5 nh\u1ea5t \u0111\u1ec3 th\u00eam ph\u1ea7n t\u1eed m\u1edbi v\u00e0o m\u1ea3ng l\u00e0 s\u1eed d\u1ee5ng ph\u01b0\u01a1ng th\u1ee9c push:<\/p>\n\n\n\n
V\u00ed d\u1ee5<\/h3>\n\n\n\nvar fruits = [\"Banana\", \"Orange\", \"Apple\", \"Mango\"];\nfruits.push(\"Lemon\"); \/\/ th\u00eam ph\u1ea7n t\u1eed m\u1edbi (Lemon) v\u00e0o fruits <\/code><\/pre>\n\n\n\nPh\u1ea7n t\u1eed m\u1edbi c\u00f3 th\u1ec3 th\u00eam v\u00e0o m\u1ea3ng b\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng thu\u1ed9c t\u00ednh \u0111\u1ed9 d\u00e0i:<\/p>\n\n\n\n
V\u00ed d\u1ee5<\/h3>\n\n\n\nvar fruits = [\"Banana\", \"Orange\", \"Apple\", \"Mango\"];\nfruits[fruits.length] = \"Lemon\"; \/\/ th\u00eam ph\u1ea7n t\u1eed m\u1edbi (Lemon) v\u00e0o fruits <\/code><\/pre>\n\n\n\nTh\u00eam ph\u1ea7n t\u1eed v\u1edbi ch\u1ec9 s\u1ed1 cao c\u00f3 th\u1ec3 t\u1ea1o ra c\u00e1c “l\u1ed7 h\u1ed5ng” kh\u00f4ng x\u00e1c \u0111\u1ecbnh trong m\u1ea3ng:<\/p>\n\n\n\n
V\u00ed d\u1ee5<\/h3>\n\n\n\nvar fruits = [\"Banana\", \"Orange\", \"Apple\", \"Mango\"];\nfruits[10] = \"Lemon\"; \/\/ th\u00eam ph\u1ea7n t\u1eed m\u1edbi (Lemon) v\u00e0o fruits <\/code><\/pre>\n\n\n\n
\n\n\n\n<\/span>V\u00f2ng l\u1eb7p ph\u1ea7n t\u1eed trong M\u1ea3ng<\/span><\/h2>\n\n\n\nC\u00e1ch t\u1ed1t nh\u1ea5t \u0111\u1ec3 th\u1ef1c hi\u1ec7n v\u00f2ng l\u1eb7p trong m\u1ea3ng l\u00e0 s\u1eed d\u1ee5ng v\u00f2ng l\u1eb7p “for”:<\/p>\n\n\n\n
V\u00ed d\u1ee5<\/h3>\n\n\n\nvar fruits, text, fLen, i;\n\nfruits = [\"Banana\", \"Orange\", \"Apple\", \"Mango\"];\n fLen = fruits.length;\n text = \"<ul>\";\n for (i = 0; i < fLen; i++) {\n text += \"<li>\" + fruits[i] + \"<\/li>\";\n }<\/code><\/pre>\n\n\n\n
\n\n\n\n<\/span>M\u1ea3ng li\u00ean k\u1ebft<\/span><\/h2>\n\n\n\nR\u1ea5t nhi\u1ec1u ng\u00f4n ng\u1eef l\u1eadp tr\u00ecnh h\u1ed7 tr\u1ee3 m\u1ea3ng v\u1edbi ch\u1ec9 s\u1ed1 t\u00ean.<\/p>\n\n\n\n
M\u1ea3ng v\u1edbi ch\u1ec9 s\u1ed1 t\u00ean \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 m\u1ea3ng li\u00ean k\u1ebft (ho\u1eb7c b\u0103m).<\/p>\n\n\n\n
JavaScript kh\u00f4ng h\u1ed7 tr\u1ee3 m\u1ea3ng v\u1edbi ch\u1ec9 s\u1ed1 t\u00ean.<\/p>\n\n\n\n
Trong JavaScript, m\u1ea3ng<\/strong> lu\u00f4n lu\u00f4n s\u1eed d\u1ee5ng ch\u1ec9 s\u1ed1 thu\u1ea7n tu\u00fd<\/strong>.<\/p>\n\n\n\nV\u00ed d\u1ee5<\/h3>\n\n\n\nvar person = [];\nperson[0] = \"\u0110\u1ee9c Anh\";\nperson[1] = \"Nguy\u1ec5n\";\nperson[2] = 30;\nvar x = person.length; \/\/person.length s\u1ebd tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 l\u00e0 3\nvar y = person[0]; \/\/person[0] s\u1ebd tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 \"\u0110\u1ee9c Anh\"<\/code><\/pre>\n\n\n\nCh\u00fa \u00fd!!<\/p>\n\n\n\n
N\u1ebfu b\u1ea1n s\u1eed d\u1ee5ng ch\u1ec9 m\u1ee5c t\u00ean, JavaScript s\u1ebd \u0111\u1ecbnh ngh\u0129a l\u1ea1i m\u1ea3ng th\u00e0nh ki\u1ec3u \u0111\u1ed1i t\u01b0\u1ee3ng ti\u00eau chu\u1ea9n.<\/p>\n\n\n\n
Sau \u0111\u00f3, t\u1ea5t c\u1ea3 c\u00e1c ph\u01b0\u01a1ng th\u1ee9c v\u00e0 thu\u1ed9c t\u00ednh s\u1ebd t\u1ea1o ra k\u1ebft qu\u1ea3 kh\u00f4ng ch\u00ednh x\u00e1c<\/strong>.<\/p>\n\n\n\n V\u00ed d\u1ee5:<\/h3>\n\n\n\nvar person = [];\nperson[\"firstName\"] = \"\u0110\u1ee9c Anh\";\nperson[\"lastName\"] = \"Nguy\u1ec5n\";\nperson[\"age\"] = 30;\nvar x = person.length; \/\/ person.length s\u1ebd tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 0\nvar y = person[0]; \/\/ person[0] s\u1ebd tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 undefined (kh\u00f4ng \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a)<\/code><\/pre>\n\n\n\n
\n\n\n\n<\/span>S\u1ef1 kh\u00e1c nhau gi\u1eefa M\u1ea3ng (Arrays) v\u00e0 \u0110\u1ed1i t\u01b0\u1ee3ng (Objects)<\/span><\/h2>\n\n\n\nTrong JavaScript, m\u1ea3ng<\/strong> l\u00e0 s\u1eed d\u1ee5ng c\u00e1c ch\u1ec9 s\u1ed1 l\u00e0 c\u00e1c con s\u1ed1 thu\u1ea7n tu\u00fd<\/strong>.<\/p>\n\n\n\nTrong JavaScript, \u0111\u1ed1i t\u01b0\u1ee3ng<\/strong> s\u1eed d\u1ee5ng ch\u1ec9 s\u1ed1 t\u00ean<\/strong>.<\/p>\n\n\n\nM\u1ea3ng l\u00e0 m\u1ed9t d\u1ea1ng \u0111\u1eb7c bi\u1ec7t c\u1ee7a \u0111\u1ed1i t\u01b0\u1ee3ng, v\u1edbi ch\u1ec9 s\u1ed1 l\u00e0 c\u00e1c con s\u1ed1.<\/p>\n\n\n\n
\n\n\n\n<\/span>Khi n\u00e0o s\u1eed d\u1ee5ng M\u1ea3ng. Khi n\u00e0o s\u1eed d\u1ee5ng \u0110\u1ed1i t\u01b0\u1ee3ng<\/span><\/h2>\n\n\n\n- JavaScript kh\u00f4ng h\u1ed7 tr\u1ee3 m\u1ea3ng li\u00ean k\u1ebft (m\u1ea3ng v\u1edbi ch\u1ec9 s\u1ed1 t\u00ean l\u00e0 v\u0103n b\u1ea3n)<\/li>
- B\u1ea1n n\u00ean s\u1eed d\u1ee5ng \u0111\u1ed1i t\u01b0\u1ee3ng<\/strong> khi b\u1ea1n mu\u1ed1n t\u00ean ph\u1ea7n t\u1eed l\u00e0 chu\u1ed7i (v\u0103n b\u1ea3n)<\/strong><\/li>
- B\u1ea1n n\u00ean s\u1eed d\u1ee5ng m\u1ea3ng<\/strong> khi b\u1ea1n mu\u1ed1n t\u00ean ph\u1ea7n t\u1eed l\u00e0 c\u00e1c con s\u1ed1<\/strong><\/li><\/ul>\n\n\n\n
\n\n\n\n<\/span>Tr\u00e1nh s\u1eed d\u1ee5ng new Array()<\/span><\/h2>\n\n\n\nB\u1ea1n s\u1eed d\u1ee5ng [] \u0111\u1ec3 thay th\u1ebf.<\/strong><\/p>\n\n\n\nC\u00f3 hai c\u00e2u l\u1ec7nh kh\u00e1c nhau, c\u1ea3 hai \u0111\u1ec1u t\u1ea1o ra m\u1ea3ng r\u1ed7ng c\u00f3 t\u00ean l\u00e0 poins:<\/p>\n\n\n\n
var points = new Array(); \/\/ C\u00e1ch kh\u00f4ng t\u1ed1t\nvar points = []; \/\/ C\u00e1ch t\u1ed1t<\/code><\/pre>\n\n\n\nC\u00f3 hai c\u00e2u l\u1ec7nh kh\u00e1c nhau \u0111\u1ec3 t\u1ea1o ra m\u1ea3ng bao g\u1ed3m 6 s\u1ed1:<\/p>\n\n\n\n
var points = new Array(40, 100, 1, 5, 25, 10) \/\/C\u00e1ch kh\u00f4ng t\u1ed1t\nvar points = [40, 100, 1, 5, 25, 10]; \/\/ C\u00e1ch t\u1ed1t<\/code><\/pre>\n\n\n\nT\u1eeb kho\u00e1 new<\/strong> l\u00e0m ph\u1ee9c t\u1ea1p code. N\u00f3 c\u00f3 th\u1ec3 t\u1ea1o ra m\u1ed9t s\u1ed1 k\u1ebft qu\u1ea3 kh\u00f4ng nh\u01b0 mong \u0111\u1ee3i:<\/p>\n\n\n\nvar points = new Array(40, 100); \/\/ T\u1ea1o ra m\u1ea3ng v\u1edbi hai ph\u1ea7n t\u1eed l\u00e0 (40 v\u00e0 100)<\/code><\/pre>\n\n\n\n\u0110i\u1ec1u g\u00ec x\u1ea3y ra n\u1ebfu t\u00f4i lo\u1ea1i b\u1ecf m\u1ed9t ph\u1ea7n t\u1eed?<\/p>\n\n\n\n
var points = new Array(40); \/\/ T\u1ea1o ra m\u1ed9t m\u1ea3ng v\u1edbi 40 ph\u1ea7n t\u1eed kh\u00f4ng \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a !!!!!<\/code><\/pre>\n\n\n\n
\n\n\n\n<\/span>L\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 nh\u1eadn bi\u1ebft m\u1ed9t m\u1ea3ng<\/span><\/h2>\n\n\n\nM\u1ed9t c\u00e2u h\u1ecfi ph\u1ed5 bi\u1ebfn l\u00e0: L\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 t\u00f4i bi\u1ebft m\u1ed9t bi\u1ebfn l\u00e0 m\u1ed9t m\u1ea3ng?<\/p>\n\n\n\n
V\u1ea5n \u0111\u1ec1 l\u00e0 to\u00e1n t\u1eed typeof<\/strong> c\u1ee7a JavaScript tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 “object” – \u0111\u1ed1i t\u01b0\u1ee3ng<\/strong>:<\/p>\n\n\n\nvar fruits = [\"Banana\", \"Orange\", \"Apple\", \"Mango\"];\n\ntypeof fruits; \/\/ tr\u1ea3 v\u1ec3 k\u1ebft qu\u1ea3 object - \u0111\u1ed1i t\u01b0\u1ee3ng<\/code><\/pre>\n\n\n\nTo\u00e1n t\u1eed typeof tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 \u0111\u1ed1i t\u01b0\u1ee3ng b\u1edfi v\u00ec m\u1ea3ng trong JavaScript l\u00e0 \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n\n\n\n
Gi\u1ea3i ph\u00e1p 1:<\/h3>\n\n\n\n
\u0110\u1ec3 gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 n\u00e0y, ECMAScript 5 \u0111\u1ecbnh ngh\u0129a ph\u01b0\u01a1ng th\u1ee9c m\u1edbi Array.isArray()<\/strong>:<\/p>\n\n\n\nArray.isArray(fruits); \/\/ tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 true<\/code><\/pre>\n\n\n\nNh\u01b0ng v\u1ea5n \u0111\u1ec1 v\u1edbi gi\u1ea3i ph\u00e1p n\u00e0y l\u00e0 ECMAScript kh\u00f4ng \u0111\u01b0\u1ee3c h\u1ed7 tr\u1ee3 trong c\u00e1c phi\u00ean b\u1ea3n c\u0169 – tr\u01b0\u1edbc \u0111\u00e2y c\u1ee7a tr\u00ecnh duy\u1ec7t.<\/p>\n\n\n\n
Gi\u1ea3i ph\u00e1p 2:<\/h3>\n\n\n\n
\u0110\u1ec3 gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 n\u00e0y, b\u1ea1n t\u1ea1o ra h\u00e0m c\u1ee7a ri\u00eang b\u1ea1n isArray():<\/p>\n\n\n\n
function isArray(x) {\nreturn x.constructor.toString().indexOf(\"Array\") > -1;\n}<\/code><\/pre>\n\n\n\nH\u00e0m \u1edf tr\u00ean lu\u00f4n tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 true n\u1ebfu \u0111\u1ed1i s\u1ed1 l\u00e0 m\u1ed9t m\u1ea3ng.<\/p>\n\n\n\n
The function above always returns true if the argument is an array.<\/p>\n\n\n\n
Hay ch\u00ednh x\u00e1c h\u01a1n: n\u00f3 tr\u1ea3 v\u1ec1 true n\u1ebfu \u0111\u1ed1i t\u01b0\u1ee3ng nguy\u00ean m\u1eabu c\u00f3 ch\u1ee9a t\u1eeb “Array”.<\/p>\n\n\n\n
Gi\u1ea3i ph\u00e1p 3:<\/h3>\n\n\n\n
To\u00e1n t\u1eed instanceof <\/strong>tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 true n\u1ebfu \u0111\u1ed1i t\u01b0\u1ee3ng \u0111\u01b0\u1ee3c t\u1ea1o b\u1edfi m\u1ed9t c\u1ea5u tr\u00fac cho s\u1eb5n (a given constructor?):<\/p>\n\n\n\nvar fruits = [\"Banana\", \"Orange\", \"Apple\", \"Mango\"];\n\nfruits instanceof Array \/\/ tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 true<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"M\u1ea3ng trong JavaScript \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 l\u01b0u tr\u1eef nhi\u1ec1u gi\u00e1 tr\u1ecb trong m\u1ed9t bi\u1ebfn duy nh\u1ea5t. V\u00ed d\u1ee5 M\u1ea3ng l\u00e0 g\u00ec? M\u1ea3ng l\u00e0 m\u1ed9t bi\u1ebfn \u0111\u1eb7c bi\u1ec7t, c\u00f3 th\u1ec3 ch\u1ee9a h\u01a1n m\u1ed9t gi\u00e1 tr\u1ecb v\u00e0o m\u1ed9t th\u1eddi \u0111i\u1ec3m. N\u1ebfu b\u1ea1n c\u00f3 m\u1ed9t danh m\u1ee5c s\u1ea3n ph\u1ea9m (v\u00ed d\u1ee5 nh\u01b0 danh s\u00e1ch t\u00ean \u00f4 t\u00f4), …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[236],"tags":[],"yoast_head":"\n
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