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Addition of two strings gives unintended result [duplicate]

This question already has answers here:
Adding two numbers concatenates them instead of calculating the sum
(24 answers)
Closed 3 years ago.
I would like to get a numeric value in a string which is in the format 1 111.
I used a regex to extract it:
([0-9]*)\s([0-9]*)
then I thought that I will obtain the correct result with this operation:
regex_result[1]*1000+regex_result[2]
But actually I just have to addition them and I do not understand why.
var str= "Bit rate : 5 333 kb/s"
var bitrate= str.match(/Bit\srate\s*:\s([0-9]*)\s([0-9]*)\s/);
console.log(bitrate);
//attempted result, but incorrect code
console.log(bitrate[1]+bitrate[2]);
//attempted correct code, but wrong result
console.log(bitrate[1]*1000+bitrate[2]);

Here, the second captured group just so happens to be 3 characters long, so multiplying the first captured group by 1000 and adding it to the second group will just so happen to produce the same result as plain concatenation.
But you have to add them together properly first. Your second attempt isn't working properly because the right-hand side of the + is a string, and a number + a string results in concatenation, not addition:
var str = "Bit rate : 5 333 kb/s"
var bitrate = str.match(/Bit\srate\s*:\s([0-9]*)\s([0-9]*)\s/);
console.log(bitrate[1] * 1000 + Number(bitrate[2]));
If the input isn't guaranteed to have exactly 3 digits in the second capturing group, the concatenation method won't work.

You can parse them as ints instead of manipulating strings
var str= "Bit rate : 5 333 kb/s"
var bitrate= str.match(/Bit\srate\s*:\s([0-9]*)\s([0-9]*)\s/);
console.log(bitrate);
console.log(parseInt(bitrate[1] * 1000) + parseInt(bitrate[2]));

Convert Large Decimal Number to String in Javascript [duplicate]

This question already has answers here:
How to deal with big numbers in javascript [duplicate]
(3 answers)
Closed 5 years ago.
I have large decimal numbers which I am getting from a request & I want to convert them to string.
So for EG:
I tried all methods converting to string
var r=12311241412412.1241523523523235
r.toString();
r+'';
''+r;
String(r);
//output
'12311241412412.1241'
//what i want
'12311241412412.1241523523523235'
All methods return the decimal numbers upto 4 digits (12311241412412.1241)
but i want all the number till end.
I also tried r.toFixed().toString() but each time the length of decimal numbers change.
What would be easy way to do this?

the problem is that 12311241412412.1241523523523235 in javascript means 12311241412412.125. whatever you do is not gonna work unless you put the whole thing in a string at the first place.
use this instead:
var r = "12311241412412.1241523523523235";

Javascript adding numbers as if they were a string [duplicate]

This question already has answers here:
Javascript (+) sign concatenates instead of giving sum of variables
(14 answers)
Closed 6 years ago.
I have been playing around with cookies for the first time, and I have saving part of it completed. The data I'm saving are numbers and the most important part of these nubers is that I can add, subtract and so on with these. However when I try to add a number to one of my saved parametres it adds them as if they were text.
Example:
I have a cookie called value, and when I want this value I use a script I found by Jeffery To that looks like this:
function readCookie(name) {
return (name = new RegExp('(?:^|;\\s*)' + ('' + name).replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&') + '=([^;]*)').exec(document.cookie)) && name[1];
}
After I have collected this cookie I want to add one to it. Lets say that value equals nine, when it should look like this: value + 1 = 10. Simple math. However it gives me this 91. Why does it do this? I know that it is because it thinks the numbers are a string of text, but how can I get this to behave like numbers?
Solution
After reading the comments I learned that i needed to put my value inside a parseInt(). So i simply modified the funtion to say:
function readCookie(name) {
return parseInt((name = new RegExp('(?:^|;\\s*)' + ('' + name).replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&') + '=([^;]*)').exec(document.cookie)) && name[1]);
}

The + operator in JavaScript can mean mathematical addition or string concatenation. The one you get is based on the implicit type of the operands. If one of the operands is a string, the other will be converted to a string and you'll get concatenation.
The trick is to do the math on the numbers first (you can surround the math portion with parenthesis or do the math in a separate statement) and then inject the result into your string.
To force a string containing a number character into a number, you can use parseInt() and parseFloat():
var result = parseInt(value, 10) + 1;
Note that with parseInt(), you should supply the optional second argument, which specifies the radix for the operation. If the first argument happens to refer to a string that contains a hex value, the result will be based on hex, not base 10. That's why 10 is used in my example.
Also note that both parseInt() and parseFloat() stop after finding the first non-valid characters that can't be treated as numbers. So, in a string like this: "Scott7Marcy9", you would get NaN.

Cookies are saved as string values as you guessed. To get your desired effect, you're going to need to parse your value. If you are absolutely sure it will be an integer, use:
parseInt(value) + 1

jQuery not returning number from an HTML tag [duplicate]

This question already has answers here:
Javascript parse float is ignoring the decimals after my comma
(10 answers)
Closed 7 years ago.
Ok so I'm having a bit of trouble returning a number from an html tag using jquery.
So lets say i have this: <p class="number">4,500.50</p> and i want to get the number from this tag using jquery, so I have the following.
var number = parseFloat($('.number').html());
But this only returns the number 4 instead of the full number. I also treied with the .text() method but the result is the same. Any ideas as to how to resolve this? Any help is appreciated.
Example jsfiddle: https://jsfiddle.net/zf1ctums/1/

Your input string has a non standard (well probably in certain contries people are used to it) format. parseFloat only knows about digits and decimal POINT. So you need to delete the commas:
var number = parseFloat($('.number').html().replace(',', ''));

The problem is that the number should be 4500,50.
You should not pass the thousand separator.
Take a look here.

Concatenates instead of Addition in Javascript [duplicate]

This question already has answers here:
Javascript concatenating numbers, not adding up
(3 answers)
Closed 7 years ago.
var tt = gas+0.1
document.write (vartt);
Duplicate

You could make use of Number function too.
var tt = Number(gas) + 0.1;
document.write(tt);

The user entered a string. If you want to do arithmetic with it instead of string concatenation, you must convert to a number. There are many different ways to do that including parseInt(gas, 10), parseFloat(gas), Number(gas) and +gas:
Here's one implementation:
var tt = parseFloat(gas) + 0.1;
document.write(tt);
Also, your document.write() statement was not correct either. The variable name is just tt, not vartt.

Unless you are using <input type="number" /> for the input, the user provided data will be a string. By default, when you try to add a string + a number it will cast that number to a string. You can do what Видул Петров suggested and add the unary + to gas to force cast it to a number, however if it's still a string that can't be cast to a number (like someone entering in the word 'five' vs '5'), youll get NaN as a result unless you have the proper control over the incoming data.