JavaScript numeric and string conversion examples

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1. Converting numbers to strings

A. To convert a number to a string, simply add an empty string to it:

Copy CodeThe code is as follows:
var n = 100;
var n_as_string = n + "";

B. To make a number more explicitly converted to a string, you can use the string () function:

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var string_value = string (number);

C. Use the ToString () method:

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String_value = Number.tostring ();

The Number object (the basic numbers are converted to the numeric object so that this method can be called) The ToString () method has an optional parameter that specifies the cardinality of the transformation. If you do not specify this parameter, the conversion will be based on a base of 10. However, you can also convert numbers according to other cardinality (numbers from 2 to 36).
For example:

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var n = 17;
binary_string = n.tostring (2); Evaluates to "10001"
Octal_string = "0" + n.tostring (8); Evaluates to "021"
hex_string = "0x" + n.tostring (16); Evaluates to "0x11"

The D. ToFixed () method converts a number to a string and displays the specified number of digits after the decimal point. It does not use exponential notation.

Copy CodeThe code is as follows:
var n = 123456.789;
n.tofixed (0); "123457"
N.tofixed (1); "123456.79"

E. toexponential () converts a number to a string using exponential notation, preceded by a 1-digit number, and a specific number of digits after the decimal point.

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var n = 123456.789;
N.toexponential (1); "1.2e+5"
N.toexponential (3); "1.235e+5"

F. Toprecision () displays a number using the specified number of significant digits, and uses exponential notation if the meaningful number of digits is not sufficient to display the entire integer portion of the number.

Copy CodeThe code is as follows:
var n = 123456.789;
N.toprecision (4); "1.235e+5"
N.toprecision (7); "123456.8"

2. Convert strings to Numbers

A. A lack of skills to convert a string to a number but it is clear that the numbers () constructor is called as a function:

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var number = number (string_value);

B. parseint () intercepts only integers, if a string begins with "0x" or "0X", parseint () resolves it to a hexadecimal number, parseint () can even accept a parameter to specify the cardinality of the number to parse, with a valid value between 2 and 36.

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parseint ("3 Blind Mice"); Returns 3
parseint ("12.34"); Returns 12
parseint ("0xFF"); Returns 255
parseint ("11", 2); Returns 3 (1 * 2 + 1)
parseint ("FF", 16); Returns 255 (15 * 16 + 15)
parseint ("ZZ", 36); Returns 1295 (35 * 36 + 35)
parseint ("077", 8); Returns 63 (7 * 8 + 7)
parseint ("077", 10); Returns 77 (7 * 10 + 7)

C. parsefloat () intercepts integers and floating-point numbers.

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Parsefloat ("3.14 meters"); Returns 3.14

D. If parseint () and parsefloat () are not able to convert the specified string to a number, they return Nan:

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parseint (' eleven '); Returns Nan
Parsefloat ("$72.47"); Returns NaN

3 How JavaScript is rounded

A. Discard the fractional part, preserving the integral portion of the
parseint (5/2)

B. Rounding up, with decimals on the integer part plus 1

Math.ceil (5/2)

C. Rounding down

Math.floor (5/2)

D. Rounding

Math.Round (5/2)

JavaScript numeric and string conversion examples