Typescript String to Number

There are several ways you can convert Typescript String to Number. The best way is to make use of the unary plus + operator or the Number global function. You can make use of the parseint or parsefloat functions. The following examples show how to make use of these functions.

Unary plus (+)

The Unary plus (+) operator converts all string representations of numbers, boolean values(true and false), and null to numbers. If the operand cannot be converted into a number, the unary plus operator will return NaN.

The following are some of the examples

  1. Tries to convert any string to a number
  2. It converts empty string / Null to 0
  3. True is 1 and False is 0
  4. Converts Octal/Hexa numbers to decimal.
  5. Works correctly on scientific notation numbers.
  6. In case it fails to convert, then returns NaN

Parseint

The parseint function parses an string and returns an integer. The syntax of the parseInt is as follows. If you do not provide the radix then it assumes the Hexadecimal number.

parseInt(string, radix)

  1. Tries to convert any string to a integer and not to floating number
  2. Converts empty strings, null, infinity, True & false to a NaN
  3. If the string begins with 0x then it treats it a Hexadecimal number.
  4. It does not recognize the octal number that begins with 0o
  5. The older browsers will treat the number starting with 0 as Octal.
  6. Ignores the Leading & trailing spaces
  7. If only the initial part of the string is a number, then it converts into number and ignores the rest.

You can make use of the radix. The radix can be from 2 to 36. Use 2 for binary, 8 for octal, 10 for decimal & 16 for HexaDecimal number.

Parsefloat

ParseFloat is another way to convert string to a number.

  1. Tries to convert any string to a decimal or an integer number
  2. Converts empty strings, null, True & false to a NaN
  3. Returns infinity as it is.
  4. It the string begins with 0x or 0o it returns zero. Does not recognize Hexa decimal or octal numbers
  5. Ignores the Leading & trailing spaces
  6. If only the initial part of the string is a number, then it converts into number and ignores the rest.

Number global function

You can also use the Number global function. It is very similar to unary plus (+)

  1. Tries to convert any string to a number
  2. It converts empty string / Null to 0
  3. True is 1 and False is 0
  4. Converts Octal/Hexa numbers to decimal.
  5. Works correctly on scientific notation numbers.
  6. In case it fails to convert, then returns NaN

Check for NaN

The string to number operation may result in a NaN. The NaN stands for not a number. It is the result of numerical operations, where the result is not a number. Hence always check if the value is NaN using the isNaN method after the conversion.

References

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