Mdthbs

A Word/Phrase for the Process of Classifying Something as a Sin

Is this curved text blend possible in Illustrator?

Solution to German Tank Problem

Why did Gandalf use a sword against the Balrog?

What does the phrase "pull off sick wheelies and flips" mean here?

Visa National - No Exit Stamp From France on Return to the UK

If clocks themselves are based on light signals, wouldn't we expect the measured speed of light to always be the same constant?

How to take the beginning and end parts of a list with simpler syntax?

Why is the result of ('b'+'a'+ + 'a' + 'a').toLowerCase() 'banana'?

The cat ate your input again!

What is a good class if we remove subclasses?

How can this older-style irrigation tee be replaced?

Simplification of numbers

Am I overreacting to my team leader's unethical requests?

Can anybody explain why using multicolumn changes the width of the four-column tabular environment?

How to remove threat that antivirus program indicates has to be manually deleted?

How to divide item stack in MC PE?

How to assign many blockers at the same time?

What is an internal dimension/glue/muglue?

Do beef farmed pastures net remove carbon emissions?

How does "Te vas a cansar" mean "You're going to get tired"?

Why did I get only 5 points even though I won?

How can I decide if my homebrew item should require attunement?

Heating Margarine in Pan = loss of calories?

Why is the result of ('b'+'a'+ + 'a' + 'a').toLowerCase() 'banana'?

JavaScript post request like a form submitHow do you access the matched groups in a JavaScript regular expression?Why is setTimeout(fn, 0) sometimes useful?What is the purpose of the var keyword and when should I use it (or omit it)?Get all unique values in a JavaScript array (remove duplicates)Storing Objects in HTML5 localStorageWhat is JSONP, and why was it created?Why does Google prepend while(1); to their JSON responses?How to decide when to use Node.js?Why does ++[[]][+[]]+[+[]] return the string “10”?

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}

34

3

I was just practising JavaScript when one of my friends came across this JavaScript code.

('b'+'a'+ + 'a' + 'a').toLowerCase()

The above code answers "banana". Can anyone explain why?

javascript

share|improve this question

edited 2 hours ago

John Kugelman

259k5858 gold badges420420 silver badges470470 bronze badges

asked 14 hours ago

Harshvardhan SharmaHarshvardhan Sharma

30133 silver badges99 bronze badges

New contributor

Harshvardhan Sharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  29
  

  
  
  
  
  
  

  
  
  because of + + 'a' === NaN
  
  – The Reason
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  5
  

  
  
  
  
  
  

  
  
  That second plus is an unary operator: +"a" is NaN.
  
  – Gerardo Furtado
  14 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  17
  

  
  
  
  
  
  

  
  
  came across this javascript code --> Where ever this code was came across surely ought to have the explanation.
  
  – Krishna Prashatt
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  And for those eager for more. See full fun list
  
  – Giddy Naya
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  19
  

  
  
  
  
  
  

  
  
  for future "learning" experience, why not do some investigating yourself. For example, remove the toLowerCase() ... replace the b, a, a, a with a, b, c, d ... which will surely make the result more apparent
  
  – Jaromanda X
  13 hours ago
  

  
  
  
  

 | 
show 7 more comments

34

3

I was just practising JavaScript when one of my friends came across this JavaScript code.

('b'+'a'+ + 'a' + 'a').toLowerCase()

The above code answers "banana". Can anyone explain why?

javascript

share|improve this question

edited 2 hours ago

John Kugelman

259k5858 gold badges420420 silver badges470470 bronze badges

asked 14 hours ago

Harshvardhan SharmaHarshvardhan Sharma

30133 silver badges99 bronze badges

New contributor

Harshvardhan Sharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  29
  

  
  
  
  
  
  

  
  
  because of + + 'a' === NaN
  
  – The Reason
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  5
  

  
  
  
  
  
  

  
  
  That second plus is an unary operator: +"a" is NaN.
  
  – Gerardo Furtado
  14 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  17
  

  
  
  
  
  
  

  
  
  came across this javascript code --> Where ever this code was came across surely ought to have the explanation.
  
  – Krishna Prashatt
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  And for those eager for more. See full fun list
  
  – Giddy Naya
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  19
  

  
  
  
  
  
  

  
  
  for future "learning" experience, why not do some investigating yourself. For example, remove the toLowerCase() ... replace the b, a, a, a with a, b, c, d ... which will surely make the result more apparent
  
  – Jaromanda X
  13 hours ago
  

  
  
  
  

 | 
show 7 more comments

I was just practising JavaScript when one of my friends came across this JavaScript code.

('b'+'a'+ + 'a' + 'a').toLowerCase()

The above code answers "banana". Can anyone explain why?

javascript

share|improve this question

edited 2 hours ago

John Kugelman

259k5858 gold badges420420 silver badges470470 bronze badges

asked 14 hours ago

Harshvardhan SharmaHarshvardhan Sharma

30133 silver badges99 bronze badges

New contributor

Harshvardhan Sharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

('b'+'a'+ + 'a' + 'a').toLowerCase()

share|improve this question

edited 2 hours ago

John Kugelman

259k5858 gold badges420420 silver badges470470 bronze badges

asked 14 hours ago

Harshvardhan SharmaHarshvardhan Sharma

30133 silver badges99 bronze badges

New contributor

Harshvardhan Sharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 2 hours ago

John Kugelman

259k5858 gold badges420420 silver badges470470 bronze badges

asked 14 hours ago

Harshvardhan SharmaHarshvardhan Sharma

30133 silver badges99 bronze badges

New contributor

Harshvardhan Sharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 2 hours ago

John Kugelman

259k5858 gold badges420420 silver badges470470 bronze badges

edited 2 hours ago

John Kugelman

259k5858 gold badges420420 silver badges470470 bronze badges

asked 14 hours ago

Harshvardhan SharmaHarshvardhan Sharma

30133 silver badges99 bronze badges

New contributor

Harshvardhan Sharma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 14 hours ago

Harshvardhan SharmaHarshvardhan Sharma

30133 silver badges99 bronze badges

1 Answer
1

active

oldest

votes

49

+'a' resolves to NaN ("Not a Number") because it coerces a string to a number, while the character a cannot be parsed as a number.
Adding NaN to "ba" turns NaN into the string "NaN" due to type conversion, gives baNaN.
And then there is an a behind, giving baNaNa.

To lowercase it becomes banana.

The space between + + is to make the first one string concatenation and the second one a unary plus (i.e. "positive") operator.
You have the same result if you use 'ba'+(+'a')+'a', which is equivalent to 'ba'+'NaN'+'a'.

share|improve this answer

edited 5 hours ago

Bergi

400k6666 gold badges633633 silver badges958958 bronze badges

answered 14 hours ago

SOFeSOFe

3,18333 gold badges2424 silver badges4747 bronze badges

• 
  
  
  

  
  7
  

  
  
  
  
  
  

  
  
  'ba'+(+'a')+'a' is equivalent to 'ba' + NaN + 'a'. The conversion to the string happens because 'ba' beeing a string as the time when 'ba' + NaN is performed. 1 + + 'a' + 1 is NaN because it is 1 + NaN + 1 and not 1 + 'NaN' + 1 which would result in 1NaN1
  
  – t.niese
  14 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I believe there is some confusion between arithmetic operators and the unary plus in your answer. Technically speaking, the unary plus does not perform an arithmetic addition.
  
  – Gerardo Furtado
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @GerardoFurtado thanks. I made a typo when I wrote unary addition instead of unary plus. But it is a numeric-related operator nonetheless.
  
  – SOFe
  14 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  I guess that's not really important. I just checked the ES3 spec and realized the term "arithmetic operator" never appeared in the spec, so it's just how we define our own words. But indeed, you're right to say that "unary plus just converts the operand to Number type" (which is a pointless operator anyway).
  
  – SOFe
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  @SOFe In my opinion the distinction is important. For better explaining, you have two different operators that use the same symbol (+). I'm using the ECMA specifications here: One is the addition operator (ecma-international.org/ecma-262/10.0/…). The other one is the unary operator (ecma-international.org/ecma-262/10.0/#sec-unary-plus-operator). They are different. To summarise, it doesn't "attempts to perform an arithmetic operation on a string", as you mentioned in your answer.
  
  – Gerardo Furtado
  14 hours ago
  
  
  

  
  
  
  

 | 
show 2 more comments

Your Answer

StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});

Harshvardhan Sharma is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f57456188%2fwhy-is-the-result-of-ba-a-a-tolowercase-banana%23new-answer', 'question_page');
}
);

Post as a guest

Name

Email

Required, but never shown

49

+'a' resolves to NaN ("Not a Number") because it coerces a string to a number, while the character a cannot be parsed as a number.
Adding NaN to "ba" turns NaN into the string "NaN" due to type conversion, gives baNaN.
And then there is an a behind, giving baNaNa.

To lowercase it becomes banana.

The space between + + is to make the first one string concatenation and the second one a unary plus (i.e. "positive") operator.
You have the same result if you use 'ba'+(+'a')+'a', which is equivalent to 'ba'+'NaN'+'a'.

share|improve this answer

edited 5 hours ago

Bergi

400k6666 gold badges633633 silver badges958958 bronze badges

answered 14 hours ago

SOFeSOFe

3,18333 gold badges2424 silver badges4747 bronze badges

• 
  
  
  

  
  7
  

  
  
  
  
  
  

  
  
  'ba'+(+'a')+'a' is equivalent to 'ba' + NaN + 'a'. The conversion to the string happens because 'ba' beeing a string as the time when 'ba' + NaN is performed. 1 + + 'a' + 1 is NaN because it is 1 + NaN + 1 and not 1 + 'NaN' + 1 which would result in 1NaN1
  
  – t.niese
  14 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I believe there is some confusion between arithmetic operators and the unary plus in your answer. Technically speaking, the unary plus does not perform an arithmetic addition.
  
  – Gerardo Furtado
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @GerardoFurtado thanks. I made a typo when I wrote unary addition instead of unary plus. But it is a numeric-related operator nonetheless.
  
  – SOFe
  14 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  I guess that's not really important. I just checked the ES3 spec and realized the term "arithmetic operator" never appeared in the spec, so it's just how we define our own words. But indeed, you're right to say that "unary plus just converts the operand to Number type" (which is a pointless operator anyway).
  
  – SOFe
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  @SOFe In my opinion the distinction is important. For better explaining, you have two different operators that use the same symbol (+). I'm using the ECMA specifications here: One is the addition operator (ecma-international.org/ecma-262/10.0/…). The other one is the unary operator (ecma-international.org/ecma-262/10.0/#sec-unary-plus-operator). They are different. To summarise, it doesn't "attempts to perform an arithmetic operation on a string", as you mentioned in your answer.
  
  – Gerardo Furtado
  14 hours ago
  
  
  

  
  
  
  

 | 
show 2 more comments

49

+'a' resolves to NaN ("Not a Number") because it coerces a string to a number, while the character a cannot be parsed as a number.
Adding NaN to "ba" turns NaN into the string "NaN" due to type conversion, gives baNaN.
And then there is an a behind, giving baNaNa.

To lowercase it becomes banana.

The space between + + is to make the first one string concatenation and the second one a unary plus (i.e. "positive") operator.
You have the same result if you use 'ba'+(+'a')+'a', which is equivalent to 'ba'+'NaN'+'a'.

share|improve this answer

edited 5 hours ago

Bergi

400k6666 gold badges633633 silver badges958958 bronze badges

answered 14 hours ago

SOFeSOFe

3,18333 gold badges2424 silver badges4747 bronze badges

• 
  
  
  

  
  7
  

  
  
  
  
  
  

  
  
  'ba'+(+'a')+'a' is equivalent to 'ba' + NaN + 'a'. The conversion to the string happens because 'ba' beeing a string as the time when 'ba' + NaN is performed. 1 + + 'a' + 1 is NaN because it is 1 + NaN + 1 and not 1 + 'NaN' + 1 which would result in 1NaN1
  
  – t.niese
  14 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I believe there is some confusion between arithmetic operators and the unary plus in your answer. Technically speaking, the unary plus does not perform an arithmetic addition.
  
  – Gerardo Furtado
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @GerardoFurtado thanks. I made a typo when I wrote unary addition instead of unary plus. But it is a numeric-related operator nonetheless.
  
  – SOFe
  14 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  I guess that's not really important. I just checked the ES3 spec and realized the term "arithmetic operator" never appeared in the spec, so it's just how we define our own words. But indeed, you're right to say that "unary plus just converts the operand to Number type" (which is a pointless operator anyway).
  
  – SOFe
  14 hours ago
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  @SOFe In my opinion the distinction is important. For better explaining, you have two different operators that use the same symbol (+). I'm using the ECMA specifications here: One is the addition operator (ecma-international.org/ecma-262/10.0/…). The other one is the unary operator (ecma-international.org/ecma-262/10.0/#sec-unary-plus-operator). They are different. To summarise, it doesn't "attempts to perform an arithmetic operation on a string", as you mentioned in your answer.
  
  – Gerardo Furtado
  14 hours ago
  
  
  

  
  
  
  

 | 
show 2 more comments

+'a' resolves to NaN ("Not a Number") because it coerces a string to a number, while the character a cannot be parsed as a number.
Adding NaN to "ba" turns NaN into the string "NaN" due to type conversion, gives baNaN.
And then there is an a behind, giving baNaNa.

To lowercase it becomes banana.

The space between + + is to make the first one string concatenation and the second one a unary plus (i.e. "positive") operator.
You have the same result if you use 'ba'+(+'a')+'a', which is equivalent to 'ba'+'NaN'+'a'.

share|improve this answer

edited 5 hours ago

Bergi

400k6666 gold badges633633 silver badges958958 bronze badges

answered 14 hours ago

SOFeSOFe

3,18333 gold badges2424 silver badges4747 bronze badges

share|improve this answer

edited 5 hours ago

Bergi

400k6666 gold badges633633 silver badges958958 bronze badges

answered 14 hours ago

SOFeSOFe

3,18333 gold badges2424 silver badges4747 bronze badges

edited 5 hours ago

Bergi

400k6666 gold badges633633 silver badges958958 bronze badges

edited 5 hours ago

Bergi

400k6666 gold badges633633 silver badges958958 bronze badges

answered 14 hours ago

SOFeSOFe

3,18333 gold badges2424 silver badges4747 bronze badges

answered 14 hours ago

SOFeSOFe

3,18333 gold badges2424 silver badges4747 bronze badges