How do I handle newlines in JSON?

Javascript Problem Overview

I've generated some JSON and I'm trying to pull it into an object in JavaScript. I keep getting errors. Here's what I have:

var data = '{"count" : 1, "stack" : "sometext\n\n"}';
var dataObj = eval('('+data+')');

This gives me an error:

unterminated string literal

With JSON.parse(data), I see similar error messages: "Unexpected token ↵" in Chrome, and "unterminated string literal" in Firefox and IE.

When I take out the \n after sometext the error goes away in both cases. I can't seem to figure out why the \n makes eval and JSON.parse fail.

Javascript Solutions

Solution 1 - Javascript

This is what you want:

var data = '{"count" : 1, "stack" : "sometext\\n\\n"}';

You need to escape the \ in your string (turning it into a double-\), otherwise it will become a newline in the JSON source, not the JSON data.

Solution 2 - Javascript

You will need to have a function which replaces \n to \\n in case data is not a string literal.

function jsonEscape(str)  {
    return str.replace(/\n/g, "\\\\n").replace(/\r/g, "\\\\r").replace(/\t/g, "\\\\t");
}

var data = '{"count" : 1, "stack" : "sometext\n\n"}';
var dataObj = JSON.parse(jsonEscape(data));

Resulting dataObj will be

Object {count: 1, stack: "sometext\n\n"}

Solution 3 - Javascript

TLDR: A solution to the author's problem.

Use String.raw literal:

var data = String.raw`{"count" : 1, "stack" : "sometext\n\n"}`;

For some reason all answers inside here focus on how to parse a JSON string representation in JavaScript, which may cause confusion regarding how to represent newlines on actual JSON. The latter is not language-dependent.

Strictly based on the question title :

How do I handle newlines in JSON?

Let's say you parse a JSON file using the following code in node (it could be any language though):


let obj = JSON.parse(fs.readFileSync('file.json'));
console.log(obj.mykey)

Below is the output for each of the possible contents of file.json:

Input 1:

{
  "mykey": "my multiline
   value"
}

Output 1:

SyntaxError: Unexpected token

Input 2:

{
  "mykey": "my multiline\nvalue"
}

Output 2:

my multiline
value

Input 3:

{
  "mykey": "my multiline\\nvalue"
}

Output 3:

my multiline\nvalue

Conclusion 1:

To represent a newline inside a json file we should use the \n character. To represent the \n we should use \\n.

How would we define each of the above inputs using JavaScript (instead of input file):

When we need to define a string containing JSON in JavaScript, things change a bit because of the special meaning that \n has also for JavaScript. But also notice how String.raw literal fixes this.

Input1:

let input1 = '{"mykey": "my multiline\nvalue"}'

//OR
let input1 = `{
  "mykey": "my multiline
   value"
}`;

//OR
let input1 = String.raw`{
  "mykey": "my multiline
   value"
}`;

console.log(JSON.parse(input1).mykey);

//SyntaxError: Unexpected token
//in JSON at position [..]

Input 2:

let input2 = '{"mykey": "my multiline\\nvalue"}'

//OR
let input2 = `{
  "mykey": "my multiline\\nvalue"
}`;

//OR (Notice the difference from default literal)
let input2 = String.raw`{
  "mykey": "my multiline\nvalue"
}`;

console.log(JSON.parse(input2).mykey);

//my multiline
//value

Input 3:

let input3 = '{"mykey": "my multiline\\\\nvalue"}'

//OR
let input3 = `{
  "mykey": "my multiline\\\\nvalue"
}`;

//OR (Notice the difference from default literal)
let input3 = String.raw`{
  "mykey": "my multiline\\nvalue"
}`;

console.log(JSON.parse(input3).mykey);

//my multiline\nvalue

Conclusion 2:

To define a json string in javascript the easiest way would be to use String.raw, because it does not require any escaping (Well apart from backtick which is escaped like this String.raw`abc${"`"}def` ).

Of course, the easiest way to create json in javascript, in general, is to convert a javascript object to json (using JSON.stringify).

Solution 4 - Javascript

According to the specification, http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf:

> A string is a sequence of Unicode code points wrapped with quotation marks (U+0022). All characters may be placed within the quotation marks except for the characters that must be escaped: quotation mark (U+0022), reverse solidus (U+005C), and the control characters U+0000 to U+001F. There are two-character escape sequence representations of some characters.

So you can't pass 0x0A or 0x0C codes directly. It is forbidden! The specification suggests to use escape sequences for some well-defined codes from U+0000 to U+001F:

\f represents the form feed character (U+000C).
\n represents the line feed character (U+000A).

As most of programming languages uses \ for quoting, you should escape the escape syntax (double-escape - once for language/platform, once for JSON itself):

jsonStr = "{ \"name\": \"Multi\\nline.\" }";

Solution 5 - Javascript

well, it is not really necessary to create a function for this when it can be done simply with 1 CSS class.

just wrap your text around this class and see the magic :D

 <p style={{whiteSpace: 'pre-line'}}>my json text goes here \n\n</p>

note: because you will always present your text in frontend with HTML you can add the style={{whiteSpace: 'pre-line'}} to any tag, not just the p tag.

Solution 6 - Javascript

You could just escape your string on the server when writing the value of the JSON field and unescape it when retrieving the value in the client browser, for instance.

The JavaScript implementation of all major browsers have the unescape command.

Example:

On the server:

response.write "{""field1"":""" & escape(RS_Temp("textField")) & """}"

In the browser:

document.getElementById("text1").value = unescape(jsonObject.field1)

Solution 7 - Javascript

You might want to look into this C# function to escape the string:

http://www.aspcode.net/C-encode-a-string-for-JSON-JavaScript.aspx

public static string Enquote(string s)  
{ 
	if (s == null || s.Length == 0)  
	{ 
		return "\"\""; 
	} 
	char         c; 
	int          i; 
	int          len = s.Length; 
	StringBuilder sb = new StringBuilder(len + 4); 
	string       t; 
 
	sb.Append('"'); 
	for (i = 0; i < len; i += 1)  
	{ 
		c = s[i]; 
		if ((c == '\\') || (c == '"') || (c == '>')) 
		{ 
			sb.Append('\\'); 
			sb.Append(c); 
		} 
		else if (c == '\b') 
			sb.Append("\\b"); 
		else if (c == '\t') 
			sb.Append("\\t"); 
		else if (c == '\n') 
			sb.Append("\\n"); 
		else if (c == '\f') 
			sb.Append("\\f"); 
		else if (c == '\r') 
			sb.Append("\\r"); 
		else 
		{ 
			if (c < ' ')  
			{ 
				//t = "000" + Integer.toHexString(c); 
				string t = new string(c,1); 
				t = "000" + int.Parse(tmp,System.Globalization.NumberStyles.HexNumber); 
				sb.Append("\\u" + t.Substring(t.Length - 4)); 
			}  
			else  
			{ 
				sb.Append(c); 
			} 
		} 
	} 
	sb.Append('"'); 
	return sb.ToString(); 
}

Solution 8 - Javascript

I used this function to strip newline or other characters in data to parse JSON data:

function normalize_str($str) {

    $invalid = array(
        'Š'=>'S', 'š'=>'s',  'Đ'=>'Dj', 'đ'=>'dj', 'Ž'=>'Z', 'ž'=>'z',
        'Č'=>'C', 'č'=>'c',  'Ć'=>'C',  'ć'=>'c',  'À'=>'A', 'Á'=>'A', 'Â'=>'A', 'Ã'=>'A',
        'Ä'=>'A', 'Å'=>'A',  'Æ'=>'A',  'Ç'=>'C',  'È'=>'E', 'É'=>'E', 'Ê'=>'E', 'Ë'=>'E',
        'Ì'=>'I', 'Í'=>'I',  'Î'=>'I',  'Ï'=>'I',  'Ñ'=>'N', 'Ò'=>'O', 'Ó'=>'O', 'Ô'=>'O',
        'Õ'=>'O', 'Ö'=>'O',  'Ø'=>'O',  'Ù'=>'U',  'Ú'=>'U', 'Û'=>'U', 'Ü'=>'U', 'Ý'=>'Y',
        'Þ'=>'B', 'ß'=>'Ss', 'à'=>'a',  'á'=>'a',  'â'=>'a', 'ã'=>'a', 'ä'=>'a', 'å'=>'a',
        'æ'=>'a', 'ç'=>'c',  'è'=>'e',  'é'=>'e',  'ê'=>'e', 'ë'=>'e', 'ì'=>'i', 'í'=>'i',
        'î'=>'i', 'ï'=>'i',  'ð'=>'o',  'ñ'=>'n',  'ò'=>'o', 'ó'=>'o', 'ô'=>'o', 'õ'=>'o',
        'ö'=>'o', 'ø'=>'o',  'ù'=>'u',  'ú'=>'u',  'û'=>'u', 'ý'=>'y', 'ý'=>'y', 'þ'=>'b',
        'ÿ'=>'y', 'Ŕ'=>'R',  'ŕ'=>'r',
        "`" => "'", "´" => "'",  '"' => ',',  '`' => "'",
        '´' => "'", '"' => '\"', '"' => "\"", '´' => "'",
        "&acirc;€™" => "'",
        "{" => "",
        "~" => "",  "–" => "-",  "'" => "'",  "     " => " ");

    $str = str_replace(array_keys($invalid), array_values($invalid), $str);

    $remove = array("\n", "\r\n", "\r");
    $str = str_replace($remove, "\\n", trim($str));

    //$str = htmlentities($str, ENT_QUOTES);

    return htmlspecialchars($str);
}

echo normalize_str($lst['address']);

Solution 9 - Javascript

I encountered that problem while making a class in PHP 4 to emulate json_encode (available in PHP 5). Here's what I came up with:

class jsonResponse {
    var $response;

    function jsonResponse() {
        $this->response = array('isOK'=>'KO', 'msg'=>'Undefined');
    }

    function set($isOK, $msg) {
        $this->response['isOK'] = ($isOK) ? 'OK' : 'KO';
        $this->response['msg'] = htmlentities($msg);
    }

    function setData($data=null) {
        if(!is_null($data))
            $this->response['data'] = $data;
        elseif(isset($this->response['data']))
            unset($this->response['data']);
    }

    function send() {
        header('Content-type: application/json');
        echo '{"isOK":"' . $this->response['isOK'] . '","msg":' . $this->parseString($this->response['msg']);
        if(isset($this->response['data']))
            echo ',"data":' . $this->parseData($this->response['data']);
        echo '}';
    }

    function parseData($data) {
        if(is_array($data)) {
            $parsed = array();
            foreach ($data as $key=>$value)
                array_push($parsed, $this->parseString($key) . ':' . $this->parseData($value));
            return '{' . implode(',', $parsed) . '}';
        }
        else
            return $this->parseString($data);
    }

    function parseString($string) {
            $string = str_replace("\\", "\\\\", $string);
            $string = str_replace('/', "\\/", $string);
            $string = str_replace('"', "\\".'"', $string);
            $string = str_replace("\b", "\\b", $string);
            $string = str_replace("\t", "\\t", $string);
            $string = str_replace("\n", "\\n", $string);
            $string = str_replace("\f", "\\f", $string);
            $string = str_replace("\r", "\\r", $string);
            $string = str_replace("\u", "\\u", $string);
            return '"'.$string.'"';
    }
}

I followed the rules mentioned here. I only used what I needed, but I figure that you can adapt it to your needs in the language your are using. The problem in my case wasn't about newlines as I originally thought, but about the / not being escaped. I hope this prevent someone else from the little headache I had figuring out what I did wrong.

Solution 10 - Javascript

As I understand you question, it is not about parsing JSON because you can copy-paste your JSON into your code directly - so if this is the case then just copy your JSON direct to dataObj variable without wrapping it with single quotes (tip: eval==evil)

var dataObj = {"count" : 1, "stack" : "sometext\n\n"};

console.log(dataObj);

Content Type	Original Author	Original Content on Stackoverflow
Question	polarbear	View Question on Stackoverflow
Solution 1 - Javascript	BlaM	View Answer on Stackoverflow
Solution 2 - Javascript	manish_s	View Answer on Stackoverflow
Solution 3 - Javascript	Marinos An	View Answer on Stackoverflow
Solution 4 - Javascript	gavenkoa	View Answer on Stackoverflow
Solution 5 - Javascript	jerryurenaa	View Answer on Stackoverflow
Solution 6 - Javascript	Victor_Magalhaes	View Answer on Stackoverflow
Solution 7 - Javascript	Ron	View Answer on Stackoverflow
Solution 8 - Javascript	ShivarajRH	View Answer on Stackoverflow
Solution 9 - Javascript	GabrielP	View Answer on Stackoverflow
Solution 10 - Javascript	Kamil Kiełczewski	View Answer on Stackoverflow

How do I handle newlines in JSON?

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Solution 2 - Javascript

Solution 3 - Javascript

How do I handle newlines in JSON?

Conclusion 1:

How would we define each of the above inputs using JavaScript (instead of input file):

Conclusion 2:

Solution 4 - Javascript

Solution 5 - Javascript

Solution 6 - Javascript

Solution 7 - Javascript

Solution 8 - Javascript

Solution 9 - Javascript

Solution 10 - Javascript

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