{"componentChunkName":"component---src-templates-blog-post-js","path":"/VariableDeclartion in Js/","webpackCompilationHash":"fbb20c27e610daab547e","result":{"data":{"site":{"siteMetadata":{"title":"Articles","author":"Aman-Sharma"}},"markdownRemark":{"id":"c3f7e7a5-69c2-5cbb-a836-c4ba3956813d","excerpt":"Ways To Declare Variables In JavaScript There are three ways to declare variables in the javascript given below:- Var Let Const Difference Between Var,Let,Const…","html":"
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    Ways To Declare Variables In JavaScript

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    There are three ways to declare variables in the javascript given below:-

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    Var

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    Let

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    Const

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    Difference Between Var,Let,Const.

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Variable Declaration with let and const and var

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//ES5\nvar x = 10;\nx = 12;\nconsole.log(x);//12\n12;
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//ES6\nlet x = 10;\nx = 12;\nconsole.log(x); //12
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//ES6\nconst y = 14;\ny = 12; //TypeError: Assignment to constant variable.\nconsole.log(y);
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Scope of Let,Const and Var

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var a //declaration\na = 2 // initialization\nlet b //declaration\nb = 12 //initialization\nvar c = 6 //declaration plus initialization in one step\nlet d = 5 //declaration plus initialization in one step\nconst a ; // SyntaxError: Missing initializer in const declaration\na = 2;\nconsole.log(a);\nconst a = 5\nconsole.log(a) //5

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1: when we start our variable with var, let is called declaration. e.g: var a; or let a;\n2: when we start our variable and assigning value it is declaration and initialization with value\n3: const cannot be declared only, you need to initialize it with declaration

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Let and const have a block scope but var has function scope.

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//ES5\nfunction adult5(age) {\n  if (age > 18) {\n    var status = 'adult';\n  }\n  console.log(status); //adult\n}\nadult5(20);
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/ ES6\nfunction adult6(age) {\n  if (age > 18) {\n    let status = 'adult';\n  }\n  console.log(status); //ReferenceError: status is not defined\n}\nadult6(20);
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1: var and let can change their value and const cannot change its value\n2: var can be accessible anywhere in function but let and const can only be accessible inside the block where they are declared.

","frontmatter":{"title":"Es6 Variable Declaration","date":"October 26, 2019","description":" Variable Declaration In (EcmaScript)"}}},"pageContext":{"isCreatedByStatefulCreatePages":false,"slug":"/VariableDeclartion in Js/","previous":{"fields":{"slug":"/typeConversion/"},"frontmatter":{"title":"TypeConversion In Js"}},"next":{"fields":{"slug":"/React-Redux /"},"frontmatter":{"title":"React Redux"}}}}}