Variable name as a string in Javascript

Question

Is there a way to get a variable name as a string in Javascript   like NSStringFromSelector in Cocoa   I would like to do like this   var myFirstName    John   alert variablesName myFirstName          myFirstName    -- gt  myFirstName John     UPDATE  I m trying to connect a browser and another program using JavaScript  I would like to send instance names from a browser to another program for callback method   FooClass   function      FooClass someMethod   function json         Do something    instanceA   new FooClass    instanceB   new FooClass    doSomethingInAnotherProcess instanceB      result will be substituted by using instanceB someMethod           From another program   evaluateJavascriptInBrowser   instanceName  someMethod  resultA         In PHP  How to get a variable name as a string in PHP

User · Answer

In ES6  you could write something like   let myVar    something   let nameObject    myVar   let getVarNameFromObject    nameObject    gt      for let varName in nameObject        return varName        let varName   getVarNameFromObject nameObject     Not really the best looking thing  but it gets the job done   This leverages ES6 s object destructuring   More info here  https   hacks mozilla org 2015 05 es6-in-depth-destructuring

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var somefancyvariable    fancy   Object keys  somefancyvariable   0      This isn t able to be made into a function as it returns the name of the function s variable      THIS DOESN T WORK function getVarName v        return Object keys  v   0        Returns  v      Edit  Thanks to  Madeo for pointing out how to make this into a function   function debugVar varObj        var varName   Object keys varObj  0       console log  Var       varName       has a value of       varObj varName               You will need call the function with a single element array containing the variable  debugVar  somefancyvariable    Edit  Object keys can be referenced as just keys in every browser I tested it in but according to the comments it doesn t work everywhere

User · Answer

You can use the following solution to solve your problem   const myFirstName    John  Object keys  myFirstName   0      returns  myFirstName

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Like Seth s answer  but uses Object keys   instead    x000D   x000D  const varToString   varObj   gt  Object keys varObj  0  x000D   x000D  const someVar   42 x000D  const displayName   varToString   someVar    x000D  console log displayName  x000D   x000D   x000D

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Since ECMAScript 5 1 you can use Object keys to get the names of all properties from an object   Here is an example    x000D   x000D     Get John   s properties  firstName  lastName  x000D  var john    firstName   John   lastName   Doe    x000D  var properties   Object keys john   x000D   x000D     Show John   s properties x000D  var message    John   s properties are      properties join        x000D  document write message   x000D   x000D   x000D

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Typically  you would use a hash table for a situation where you want to map a name to some value  and be able to retrieve both    x000D   x000D  var obj     myFirstName   John     x000D  obj foo    Another name   x000D  for key in obj  x000D      console log key          obj key    x000D   x000D   x000D

User · Answer

When having a function write a function that changes different global variables values it is not always myfirstname it is whatever happens to be passing through  Try this worked for me   Run in jsfiddle  var jack    jill   function window getVarName what      for  var name in window          if  window name   what      return name         return        document write window getVarName jack      Will write to the window  jack

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Probably pop would be better than indexing with  0   for safety  variable might be null    const myFirstName    John  const variableName   Object keys  myFirstName   pop    console log  Variable   variableName  with value    variable          returns  Variable myFirstName with value  John

User · Answer

var x   2  for o in window       if window o      x         alert o            However  I think you should do like  karim79

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best way using Object keys    example for getting multi variables names in global scope    multi varibles for testing var x   5   b   true   m   6   v    quot str quot       pass all varibles you want in object function getVarsNames v               getting keys or names       let names   Object keys v          return array has real names of varibles      return names       testing if that work or not  let VarsNames   getVarsNames  x   b   m   v     console log VarsNames      output is array  x   b   m   v

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I ve created this function based on JSON as someone suggested  works fine for my debug needs   x000D   x000D  function debugVar varNames   x000D  let strX       x000D  function replacer key  value   x000D      if  value     undefined  return  undef   x000D      return value x000D            x000D  for  let arg of arguments   x000D  let lastChar  x000D      if  typeof arg     string    x000D          let  arg   JSON stringify arg  replacer   x000D           arg    arg replace          x000D           arg    arg replace                      x000D           arg    arg replace    g       x000D           arg    arg replace    g      x000D          strX   arg  x000D       else  x000D      strX  arg  x000D      lastChar   arg arg length-1   x000D        x000D      if  arg   arguments arguments length-1  amp  amp lastChar        strX        x000D    x000D  console log strX      x000D    x000D  let a   42  b   3  c  x000D  debugVar  Begin    a b c   end   x000D   x000D   x000D

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This worked using Internet Explorer  9  10 and 11   Google Chrome 5    x000D   x000D      x000D  var myFirstName    Danilo   x000D  var varName   Object keys  myFirstName 0   0   x000D  console log varName   x000D   x000D   x000D    Browser compatibility table  https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Object keys

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This works for basic expressions  const nameof   exp   gt  exp toString   match       w     1     Example  nameof      gt  options displaySize     Snippet    x000D   x000D  var nameof   function  exp    return exp toString   match       w     1      x000D  var myFirstName    Chuck   x000D  var varname   nameof function      return window myFirstName      x000D  console log varname   x000D   x000D   x000D

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Shortest way I have found so far to get the variables name as a string   x000D   x000D  const name   obj   gt  Object keys obj  0    const whatsMyName    Snoop Doggy Dogg    console log   Variable name is      name   whatsMyName         result  Variable name is  whatsMyName x000D   x000D   x000D

User · Answer

You can reflect on types in javascript and get the name of properties and methods but what you need is sth like Lambda Expressions Trees in  NET  I think it s not be possible due to dynamic nature and lack of static type system in javascript

User · Answer

No  there is not  Besides  if you can write variablesName myFirstName   you already know the variable name   myFirstName

User · Answer

I needed this  don t want to use objects  and came up with the following solution  turning the question around    Instead of converting the variable name into a string  I convert a string into a variable    This only works if the variable name is known of course   Take this   var height   120  testAlert height     This should display   height  120   This can be done like this   function testAlert ta        a   window ta       alert ta          a       var height   120  testAlert  height       displays  height  120   So I use the string  height  and turn that into a variable height using the window   command

[javascript] Variable name as a string in Javascript

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