Why is typeof equaling a string in this for loop?

Question

If I run this code in the jsFiddle it correctly seems to log the typeof, first six are strings then the seventh index is an object. However in my personal local code, all seven indexes are a string, and if you copy and paste this code into the console it logs all also as a string. Why is this?

jsFiddle: https://jsfiddle.net/xcuje23q/

JS:

var someArray = ['Mike','Brett','Kim','Steve','Amy','Tanner',{name:'Oliver'}];

for(var i = 0; i < someArray.length; i++){

  var name = someArray[i];
  console.log(typeof name)

}

Yes, I know that is an object, but if you paste this code and run it in the console, all seven typeof are strings, the last should be an object not a string right? — Chipe, Mar 02 '16 at 05:29
[`name`](https://developer.mozilla.org/en-US/docs/Web/API/Window/name) is a reserved global in browsers and can only be assigned a string value. Assigning anything else automatically converts it to a string. — Jonathan Lonowski, Mar 02 '16 at 05:29

score 8 · Accepted Answer · edited May 23 '17 at 11:45

8

Javascript follows function level scope, there is property name for window object(global) and in console, it refers to property of window as it is executed in global context(window.name)

Use IIFE((function(){ /*your code */ })()) to get expected output as name does not belong to window anymore. function(){ } has its own scope

(function() {
  var someArray = ['Mike', 'Brett', 'Kim', 'Steve', 'Amy', 'Tanner', {
    name: 'Oliver'
  }];

  for (var i = 0; i < someArray.length; i++) {
    var name = someArray[i];
    console.log(typeof name)
  }
})()

<script src="http://gh-canon.github.io/stack-snippet-console/console.min.js"></script>

Edit: Refer WebKit Bugzilla for some interesting discussion about window.name

edited May 23 '17 at 11:45

Community

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answered Mar 02 '16 at 05:28

Rayon

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Ah, that makes sense. Thanks! – Chipe Mar 02 '16 at 05:30
what do you mean by IIFE? – Akash KC Mar 02 '16 at 05:31
2

@LolCoder아카쉬 [Immediately-invoked function expression](http://stackoverflow.com/questions/8228281/what-is-the-function-construct-in-javascript). – Jonathan Lonowski Mar 02 '16 at 05:32
Oh !!! Used to stick with this practice but never acquainted with this acronym. Thanks !!! – Akash KC Mar 02 '16 at 05:36

Kaushik · Answer 2 · 2016-03-02T06:52:50.783

There is one more alternative you may like. Do not use the variable name. Check this fiddle

var someArray = ['Mike','Brett','Kim','Steve','Amy','Tanner',{name:'Oliver'}];

for(var i = 0; i < someArray.length; i++){

  console.log(typeof someArray[i])
  // o/p 6 string and 1 object

}

OR

var someArray = ['Mike','Brett','Kim','Steve','Amy','Tanner',{name:'Oliver'}];

for(var i = 0; i < someArray.length; i++){

  var name2 = someArray[i]; // change name of the variable.
  console.log(typeof name2)

}

Why is typeof equaling a string in this for loop?

2 Answers2