How do you convert a string to a number in javascript?
There are two main ways to convert a string to a number in javascript. One way is to parse it and the other way is to change its type to a Number. All of the tricks in the other answers (e.g. unary plus) involve implicitly coercing the type of the string to a number. You can also do the same thing explicitly with the Number function. Show
Parsing
parseInt and parseFloat are the two functions used for parsing strings to numbers. Parsing will stop silently if it hits a character it doesn't recognise, which can be useful for parsing strings like "92px", but it's also somewhat dangerous, since it won't give you any kind of error on bad input, instead you'll get back NaN unless the string starts with a number. Whitespace at the beginning of the string is ignored. Here's an example of it doing something different to what you want, and giving no indication that anything went wrong:
It's good practice to always specify the
radix as the second argument. In older browsers, if the string started with a 0, it would be interpreted as octal if the radix wasn't specified which took a lot of people by surprise. The behaviour for hexadecimal is triggered by having the string start with 0x if no radix is specified, e.g. Changing the Type of a String to a Number All of the other tricks mentioned above that don't use parseInt, involve implicitly coercing the string into a number. I prefer to do this explicitly,
This has different behavior to the parse methods (although it still ignores whitespace). It's more strict: if it doesn't understand the whole of the string than it returns Obviously, converting to a Number gives you a value that might be a float rather than an integer, so if you want an integer, you need to modify it. There are a few ways of doing this:
Any bitwise operator (here I've done a bitwise or, but you could also do double negation as in an earlier answer or a bitshift) will convert the value to a 32bit integer, and most of them will convert to a signed integer. Note that this will not do want you want for large integers. If the integer cannot be represented in 32bits, it will wrap.
To work correctly with larger numbers, you should use the rounding methods
Bear in mind that coeercion understands exponential notation and Infinity, so Custom It's unlikely that either of these methods do exactly what you want. For example, usually I would want an error thrown if parsing fails, and I don't need support for Infinity, exponentials or leading whitespace. Depending on your usecase, sometimes it makes sense to write a custom conversion function. Always check that the output of Number or one of the parse methods is the sort of number you expect. You will almost certainly want to use Sanchithasr Posted on Dec 16, 2020 • Updated on Aug 19, 2021 1. Using parseInt()
Enter fullscreen mode Exit fullscreen mode 2. Using Number()
Enter fullscreen mode Exit fullscreen mode 3. Using Unary Operator (+)The unary plus operator (
Enter fullscreen mode Exit fullscreen mode 4. Using parseFloat()
Enter fullscreen mode Exit fullscreen mode 5. Using Math.floor()The
Enter fullscreen mode Exit fullscreen mode 6. Multiply with numberMultiplying the string value with the
Enter fullscreen mode Exit fullscreen mode 7. Double tilde (~~) OperatorWe can use the double tilde operator to convert the string to number.
Enter fullscreen mode Exit fullscreen mode Here is the comparison of the ways mentioned performance wise. Comment below if you know more methods. How can a string be converted to a number?You convert a string to a number by calling the Parse or TryParse method found on numeric types ( int , long , double , and so on), or by using methods in the System. Convert class. It's slightly more efficient and straightforward to call a TryParse method (for example, int.
How do I convert a string to a number in TypeScript?Use the Number() object to convert a string to a number in TypeScript, e.g. const num1 = Number(str) . ... . Use the parseInt() function to convert a string to a number, e.g. const num1 = parseInt(str) . ... . To extract a number from a string in TypeScript, call the replace() method, e.g. str.. How do you convert to int in JavaScript?In JavaScript parseInt() function (or a method) is used to convert the passed in string parameter or value to an integer value itself. This function returns an integer of base which is specified in second argument of parseInt() function.
What does number () in JavaScript do?The Number() method converts a value to a number. If the value cannot be converted, NaN is returned.
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