Javascript How to define multiple variables on a single line

Question

Reading documentation online  I m getting confused how to properly define multiple JavaScript variables on a single line   If I want to condense the following code  what s the proper JavaScript  strict  way to define multiple javascript variables on a single line   var a   0  var b   0    Is it   var a   b   0    or  var a   var b   0     etc

User · Answer

There is no way to do it in one line with assignment as value.

var a = b = 0;

makes b global. A correct way (without leaking variables) is the slightly longer:

var a = 0, b = a;

which is useful in the case:

var a = <someLargeExpressionHere>, b = a, c = a, d = a;

User · Answer

Why not doing it in two lines  var a  b  c  d        All in the same scope a   b   c   d   1     Set value to all   The reason why  is to preserve the local scope on variable declarations  as this  var a   b   c   d   1   will lead to the implicit declarations of b  c and d on the window scope

User · Answer

Specifically to what the OP has asked  if you want to initialize N variables with the same value  e g  0   you can use array destructuring and Array fill to assign to the variables an array of N 0s    x000D   x000D  let  a  b  c  d    Array 4  fill 0   x000D   x000D  console log a  b  c  d   x000D   x000D   x000D

User · Answer

You want to rely on commas because if you rely on the multiple assignment construct  you ll shoot yourself in the foot at one point or another   An example would be    gt  gt  gt  var a   b   c        gt  gt  gt  c push 1   1   gt  gt  gt  a  1    They all refer to the same object in memory  they are not  unique  since anytime you make a reference to an object   array  object literal  function   it s passed by reference and not value  So if you change just one of those variables  and wanted them to act individually you will not get what you want because they are not individual objects   There is also a downside in multiple assignment  in that the secondary variables become globals  and you don t want to leak into the global namespace    function      var a   global   5       alert window global     5   It s best to just use commas and preferably with lots of whitespace so it s readable   var a   5     b   2     c   3     d          e

User · Answer

Here is the new ES6 method of declaration multiple variables in one line    x000D   x000D  const person     name   Prince   age  22  id  1    x000D   x000D  let  name  age  id    person  x000D   x000D  console log name   x000D  console log age   x000D  console log id   x000D   x000D   x000D      Your variable name and object index need be same

User · Answer

note you can only do this with Numbers and Strings  you could do     var a  b  c  a   b   c   0    but why   c       c   1  b   0  a   0

User · Answer

Using Javascript s es6 or node  you can do the following   var  a b c d     0 1 2 3    And if you want to easily print multiple variables in a single line  just do this   console log a  b  c  d       0 1 2 3   This is similar to  alex gray  s answer here  but this example is in Javascript instead of CoffeeScript   Note that this uses Javascript s array destructuring assignment

[javascript] Javascript How to define multiple variables on a single line?

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