difference between 22let 22 and 22var 22 3f

Solutions on MaxInterview for difference between 22let 22 and 22var 22 3f by the best coders in the world

showing results for - "difference between 22let 22 and 22var 22 3f"
Maria
21 Oct 2018
1var is function scoped and let is block scoped. Let's say you have:
2function understanding_var() {
3	if (1 == 1) {
4    	var x = 5;
5        console.log('the value of x inside the if statement is ' + x);
6    }
7    console.log(x);
8} 
9//output: the value of x inside the if statement is 5
10		  5
11
12function understanding_let() {
13	if (1 == 1) {
14    	let x = 5;
15        console.log('the value of x inside the if statement is ' + x);
16    }
17    console.log(x);
18} 
19//output: the value of x inside the if statement is 5
20		  Uncaught ReferenceError: x is not defined
21          
22var is defined throughout the entire function, even if it's inside the if 
23statement, but the scope of let is always within the curly braces, not outside
24it, even if the conditional statement is inside the function.
Enrico
14 Aug 2017
1In simple words 'var' is function scoped and 'let' is block scoped
Theo
05 Oct 2019
1let a = 'hello'; // globally scoped
2var b = 'world'; // globally scoped
3console.log(window.a); // undefined
4console.log(window.b); // 'world'
5var a = 'hello';
6var a = 'world'; // No problem, 'hello' is replaced.
7let b = 'hello';
8let b = 'world'; // SyntaxError: Identifier 'b' has already been declared
Ramsey
19 May 2019
1// var is function-scoped, so redeclaring it in a block will cause its value outside the block to change as well:
2
3var one = 'one: declared outside the block';
4
5if (true === true) {
6  var one = 'one: declared inside the block'; // notice: we redeclare 'one' here
7  console.log(one); // prints 'one: declared inside the block'
8}
9
10console.log(one); // also prints 'one: declared inside the block', because the variable was redeclared in the 'if' block. The outer 'var' variable was therefore destroyed and replaced by inner var variable.
11
12// 'let' is block-scoped, so redeclaring a 'let' variable inside of a block creates a different 'let' variable with the same name whose scope is inside the block:
13
14let two = 'two: declared outside the block';
15
16if (true === true) {
17  let two = 'two: declared inside the block';
18  console.log(two); // prints 'two: declared inside the block'
19}
20
21console.log(two); // prints 'two: declared outside the block', because two declared inside the block is a separate variable. The 'let' variables are unrelated and therefore are unaffected by each other.
queries leading to this page
difference beteween var and letdifff between var and letdifference var and let javascriptwhat the difference between var and let4 difference between let and var in javascriptdifference beteen let and varthe difference between var and letdifference between let an d var in jswhat is difference between letdifference between var and let in node jsdifference between let cont and varvar let differencevar and letwhat 27s the difference between using let and var to declare a variable in es6 3fdifferences between var o letdifference between let an varwhats the diffrent between var and letdiff between let and varjs difference between var and letdiff var and letdifference in var and letjavascript let var differnecedifference between var let and consdifference between let put and vardiff bw var and letvar letdiff let vs vardifference of let and vardifference beween let 2c const 26 vardifference between variable created using let 2c var and consvar e let differencejavascript let and vardifference between let and var 5cdifference between var and let in javascript in hindidiffernce between let and vardifference between var ans letdifference bw var let4 what is the difference between var and letjavascript let vs functiondifference between let vs varjs whats the difference between let 2c var 2c and no keyworddifference var vs letwhat is the difference between let 2cvar and const in javascriptdifference b 2fw var and letvar or let javascriptdifference btwn var and lethow is let different than var javascriptwhere and let in javascriptwhat is the diffence between the let and var in javascpritdifference between let const and var in javascriptwhat is let vs varjs var vs letdiffrent between var and letjavascript var vs let 27what are diffrents between let and var 3fnode js difference between let and varjs use var or letdifference between 22let 22 and 22var 22 3flet and var difference jsjavqascript var vs let diference between var and letlet var difference javascriptlet function or var function javascriptjavascript let vs var differencewhat is defferint bettwen let and vardifference between var and let in jslet and var in javascriptthe difference between a var and a letwhat are the difrences between var and letjavascript let vs varwhat is the difference btw let and vardifference between let and var jdwhen to use var and let in javascriptdiffrence let vardifference between var and let javascfiptwhat is the difference between var and let keywordvar or letwhat are the differences between variables created using let 2c var 2c and const 3f 2adifference between let 2c var 3fwhy difference between let and varvariable and let differencewhat is the difference between declaring a variable with let and without letlet and var keyword differencelet and var differencedifference bwtween var and letlet and var difference in javascriptthe diffrence between var and letmain difference between let and varlet and var difference with exampledifference between let var and costdifference between let and normal variable in jsdifference between a variable and letwhere to use var and letwhat is the difference between let and var in javascript what is the difference between let and var 3flet vs var in functionjavascript var or letwhat 27s the difference between 22var 22 vs 22let 22 in javascript 3fdifference var et letvar vs let javascriptdiference var and letdifference between using let and var in nodejswhat is deffrent between var and letusing var instead of letdiffrence between var and letvar and let differences4 what is the difference between var and let 3fvar let and conts differencedifference between var const 26 let in javascriptdifference between 22let 22 and 22var 22 3f 27 27differ betwen var and letdifference between let and var in javascriptwhat is dif between var and letwhat is the difference btw let and var 3flet in javascript vs vardifference betweeen var letdifference between let and var 3fdifference between let const and var javascriptwhat is difference between var and letdifference between let and var in javascript with examplevar vs letwhat is the difference between var and let in javascriptdifference between var and let jsts differende between 5bvar 5d and var 5b 5dlet var javascriptdiff between let and var in javascriptdifference between javascript var and letdifference between let and var difference between const 2c let and var in jswhats the difference between let and vardifference let varjs differnce between let and varthe difference between var and let in jsjavasript what is the difference betwen let and varin java script will var and let do the same thingdifference between var and let and constwhat 27s the difference between using let and var in javascriptdifference beetwen var and let in jsdiffernece between var and letvar vas letvar vs let differencevar and let in javascriptvar vs cast vs letdoes changing var to let make a big difference in javascriptdifference between let 2cvar and constwhat is difference between let and var in javascriptjs diff between let and arrjavascript difference var letdifferemce betwween let and vardifference between const var and let javascriptwhat is diff between var and letdiff between let vardifferenec between var and let jsdefrent between let and var in jsjs var scope vs letjs difference between let and varvar and let differencedifference b 2fw let and var in jswhen to use let vs varlet vas varwhat are the differences between variables created using let 2c var 2c and const 3f 2a 3fdiffernce between var and letdifference between let and var and const in javascriptwhat is different between let and varjavascript difference between let and varlet vs varlet var differencelet var difference jsexample diff betwenn let and vardifferent between var and letdifference between var and let javascriptwhat is difference between let and var and const in javascriptdifference wetween let and vardifference between var const and letjavascript difference between var and letdifference in let and vardifference betweeen var and letdiffernece between var and let jsdifference between var and let in javascriptwhat is the difference between let and var in jsdifference between let and varhow does let difference from var in javascriptwhat to use let vs var jsdiffernece between let and var examplesvar let difference jswhat is teh difernece bwetween var and letdiffrence between let and varvar versus letdifferences between var and letla difference const var letdifference var letdifferent between using let vs vardifferences between let and varlet and varwhen to use var vs letwht is difference between let 2c const and varthe difference between var and let in javascriptvar let in javascriptdifference between let and var in jsvar and let in jsdifference between let and var keywordwhat is the difference between let and var 3fwhat is t difference between var and letlet var as type 3ddifferece between var and letswhat is the difference bettween var and letlet vs var javascriptwhat is the difference between variables created using let 2c var 2c and const 3fjavascript 2b difference between let and varwhat is difference let and vardifference between cont var and letdifference between const let and varwhat is the difference between var let and const in javascriptvar and let difference in jsdifferentiate between let and varnodejs let vs varvar vs let vswhat is the difference between var and letdifference between let and let 21in javascript the main differences between let and var variable declarations arewhat is the difference between const var and let in javascriptdifference between var const and let in javascriptdiif between var and letdifference between let and var in javascript w3schoolsdiff c3 a9rence var et let javascriptdifference between 22let 22 and 22var 22 3f 27let vs var differencejavascript var vs letdifference between const var and letwhat is the difference between let and vardifference btw var and letdifference var and letdifferent between let and vardiffrence between let and varedifference betwwen let in and let ofdif between let varvar vs let jswhat difference between let and vardiff b let and var jslet vs var jsjavascript differences with let and varwhat is the difference between var and let and why is let preferred 3fdifference between 22let 22 and 22var 22 3f 27 27 27diff between var and letdifference between var const and letrdifference betweeen let and vardifference between var an letlet and var diff in javascriptdifferencer between let and vardifference between using 22let 22 and 22var 22 3f 2a what are the differences between variables created using let 2c var or const 3f2 what is the difference between let and var 3fdifference between let var constwhat is the difference between let cont and vardiff b 2fw let and var in jsjs different between let and varjs let vs varduffreant between let or vardiffernece between let and varbetween var 2c let 2cjs difference let varwhat is the difference between e2 80 9cvar e2 80 9d and e2 80 9clet e2 80 9d in javascript 3fdifferance between var and letwhat 27s the difference between let and var in jslet vs var in javascriptlet var difference typescriptdifference between var and letwaht is difference between var and letvar vs let in javascriptjavascript var vs let vsjavascript different let and varjquery var or letvar or let in jsdiff beetweeb vr and let in jsvar vsvar vs letdifference between let an cardifference of var and letdifference between var and let in jquerywhat is difference between var and let in jsjavascript scope difference let var explainedlet vs var in forvar difference letvar vs let in jsdifferneces bewteen the var and let keyword let or varjavascript let var differencedifference let and vardifference in let and var in javascriptwhat 27s the difference between let and var in javascriptlet vs var in jsdifference between let and var javascriptwhat is the differance between let and varjavascript difference let varwhat is the difference between let or varmajor difff between let andd var consstdifference between var and let in for loopwhat is difference between var and let in javascriptjavascript var and let differencedifference let and var javascriptlet jswhat 27s the difference between let and vardifference between var let costdifferenve between let and var in javascriptjavascript let or varthe difference between let and vardifference between var let and varjava script var vs letdifference of let or var in jsuse var instead of let jswhat is the differnce between let and vardifference b 2fw let and varjavascript let or var 3fdifference between let 2c const and var in javascriptlet and var difference exampledifference between let var javascriptvar js vs letdifference between 22let 22 and 22var 22 3f