parseFloat()

parseFloat(value, defaultValue): number

Parses a string to a float, returning default if invalid.

note

Returns default for NaN, Infinity, and invalid strings. Assumes non-nullish input.

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Parameters

value: string

The string value to parse.

defaultValue: number

The value to return if parsing fails.

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Returns: number

The parsed float or default value.

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See Also

parseFloatDef

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Since

2.0.0

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Example

parseFloat('42.99', 0);    // => 42.99
parseFloat('invalid', 0);  // => 0
parseFloat('Infinity', 0); // => 0
parseFloat('NaN', 100);    // => 100

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How it works?

Parses a string to a float, returning default if invalid.

Validation Flow

Common Inputs

Value	Default	Result
'42.99'	0	42.99
'invalid'	0	0
'Infinity'	0	0
'NaN'	100	100
'3.14abc'	0	3.14

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Use Cases

Parse floating-point numbers 📌

Convert a string to a float, with a required default value for failures. Essential for reading configuration values or user input strings.

#parse#float#decimal#conversion#default#safe

const taxRate = parseFloat(env.TAX_RATE, 0.2);

Safeguard against NaN

Ensure a calculation never propagates NaN from bad input. Critical for financial or scientific calculations.

#safeguard#NaN#validation#calculations#safety#fallback

const validValue = parseFloat(userInput, 0); // Returns 0 if input is "abc"