{"id":74323,"date":"2018-05-04T15:32:04","date_gmt":"2018-05-04T13:32:04","guid":{"rendered":"https:\/\/michelpiallier.info\/blog\/?p=74323"},"modified":"2023-03-15T10:25:06","modified_gmt":"2023-03-15T09:25:06","slug":"es6-let-et-const","status":"publish","type":"post","link":"https:\/\/michelpiallier.info\/blog\/es6-let-et-const\/","title":{"rendered":"ES6 – let et const"},"content":{"rendered":"
\n
\nEn JavaScript ES6, il existe plusieurs fa\u00e7ons de d\u00e9clarer des variables, notamment avec le mot-cl\u00e9 “let” et “const”. Les variables d\u00e9clar\u00e9es avec “let” peuvent \u00eatre r\u00e9affect\u00e9es, tandis que les variables d\u00e9clar\u00e9es avec “const” ne peuvent pas \u00eatre r\u00e9affect\u00e9es apr\u00e8s leur d\u00e9claration.
\nIl est important de noter que les variables d\u00e9clar\u00e9es avec “let” ou “const” ont une port\u00e9e de bloc. Cela signifie que si vous d\u00e9clarez une variable dans une boucle ou dans une fonction, elle ne sera accessible qu’\u00e0 l’int\u00e9rieur de ce bloc.(contrairement \u00e0 var)<\/p>\n

\n\t\t\t\tlet\t\t\t<\/h4>\n
\n

Les variables d\u00e9clar\u00e9es avec “let” peuvent \u00eatre r\u00e9affect\u00e9es.<\/p>\n

\r\n\r\nlet x = 1;\r\n\r\nif (x === 1) {\r\n  let x = 2;\r\n  console.log(x);\r\n  \/\/ r\u00e9sultat: 2\r\n}\r\nconsole.log(x);\r\n\/\/ r\u00e9sultat: 1\r\n<\/code>\r\n<\/pre>\n<\/p><\/div>\n
\n\t\t\t\tconst\t\t\t<\/h4>\n
\n
Les variables d\u00e9clar\u00e9es avec “const” ne peuvent pas \u00eatre r\u00e9affect\u00e9es apr\u00e8s leur d\u00e9claration.
\nCe sont des constante accessibles uniquement en lecture.
\nL’identifiant ne peut pas \u00eatre r\u00e9affect\u00e9.<\/strong><\/p>\n
\r\n\r\nconst NOMBRE = 42;\r\ntry {\r\n  NOMBRE = 99;\r\n} catch(err) {\r\n  console.log(err);\r\n  \/\/ r\u00e9sultat esp\u00e9r\u00e9 : message d'erreur d\u00e9pendant du navigateur\r\n }\r\nconsole.log(NOMBRE);\r\n\/\/ r\u00e9sultat esp\u00e9r\u00e9 : 42\r\n<\/code>\r\n<\/pre>\n<\/p><\/div>\n
\n\t\t\t\tJsfiddle\t\t\t<\/h4>\n
\n
Testez vos propres exemples sous Jsfiddle. Cliquez ici<\/a>\n\t\t<\/div>\n<\/div>\n<\/div>\n
<\/p>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_s2mail":""},"categories":[180],"tags":[],"yoast_head":"\nES6 - let et const<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/michelpiallier.info\/blog\/es6-let-et-const\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"ES6 - let et const\" \/>\n<meta property=\"og:url\" content=\"https:\/\/michelpiallier.info\/blog\/es6-let-et-const\/\" \/>\n<meta property=\"og:site_name\" content=\"Pense-b\u00eates des langages du Web\" \/>\n<meta property=\"article:published_time\" content=\"2018-05-04T13:32:04+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-03-15T09:25:06+00:00\" \/>\n<meta name=\"author\" content=\"Michel PIALLIER\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u00c9crit par\" \/>\n\t<meta name=\"twitter:data1\" content=\"Michel PIALLIER\" \/>\n\t<meta name=\"twitter:label2\" content=\"Dur\u00e9e de lecture estim\u00e9e\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/michelpiallier.info\/blog\/es6-let-et-const\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/michelpiallier.info\/blog\/es6-let-et-const\/\"},\"author\":{\"name\":\"Michel PIALLIER\",\"@id\":\"https:\/\/michelpiallier.info\/blog\/#\/schema\/person\/8a9d28b0899a7f9428a87647928c8709\"},\"headline\":\"ES6 – let et const\",\"datePublished\":\"2018-05-04T13:32:04+00:00\",\"dateModified\":\"2023-03-15T09:25:06+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/michelpiallier.info\/blog\/es6-let-et-const\/\"},\"wordCount\":181,\"publisher\":{\"@id\":\"https:\/\/michelpiallier.info\/blog\/#\/schema\/person\/8a9d28b0899a7f9428a87647928c8709\"},\"articleSection\":[\"ES6 - 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