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June 20, 2008 by Blogging Developer

The JavaScript parseFloat() function, parses a string and returns the first floating point number in the string.

The parseFloat() function determines if the first character in the string argument is a number, parses the string from left to right until it reaches the end of the number, discards any characters that occur after the end of the number, and finally returns the number as a number (not as a string).

Only the first number in the string is returned, regardless of how many other numbers occur in the string.

If the first character in the string is not a number, the function returns the Not-a-Number value NaN.

Here are some examples about Javascript parseFloat() method:

document.write(" " + parseFloat("15"))
document.write(" " + parseFloat("12.12345"))
document.write(" " + parseFloat("45.00000000"))
document.write(" " + parseFloat("23.348 44.218 55.405"))
document.write(" " + parseFloat(" 55 aardvarks"))
document.write(" " + parseFloat("Year 2002"))

The outputs will be:

15
12.12345
45
23.348
55
NaN