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parseFloat()

Baseline
Widely available

This feature is well established and works across many devices and browser versions. Its been available across browsers since 2015 ..

parseFloat() ( )

In this article

function circumference(r) {
  return parseFloat(r) * 2.0 * Math.PI;
}

console.log(circumference(4.567));
// Expected output: 28.695307297889173

console.log(circumference("4.567abcdefgh"));
// Expected output: 28.695307297889173

console.log(circumference("abcdefgh"));
// Expected output: NaN


parseFloat()

, .

, . , NaN.

parseFloat - , .

parseFloat , . , (+ -), (0-9), , , , , . .

, parseFloat NaN.

, NaN - . , parseFloat NaN , isNaN. NaN , NaN.

parseFloat Infinity (""). isFinite, , (not Infinity, -Infinity, NaN).

parseFloat

3.14

parseFloat(3.14);
parseFloat('3.14');
parseFloat('314e-2');
parseFloat('0.0314E+2');
parseFloat('3.14-   ');

var foo = Object.create(null);
foo.toString = function () { return "3.14"; };
parseFloat(foo);

var foo = Object.create(null);
foo.valueOf = function () { return "3.14"; };
parseFloat(foo);

parseFloat NaN

NaN

js
parseFloat("FF2");

Specification
ECMAScript 2027 LanguageSpecification
# sec-parsefloat-string

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