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Number.parseFloat()

20159

Number.parseFloat() NaN

function circumference(r) {
  if (Number.isNaN(Number.parseFloat(r))) {
    return 0;
  }
  return parseFloat(r) * 2.0 * Math.PI;
}

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

console.log(circumference("abcdefgh"));
// Expected output: 0

js
Number.parseFloat(string)

string

string

NaN

Number.parseFloat parseFloat

parseFloat()

js
Number.parseFloat === parseFloat; // true

parseFloat()
ECMAScript 2027 LanguageSpecification
# sec-number.parsefloat

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  1. JavaScript
  2. Number
    1. Number()
    1. Number.isFinite()
    2. Number.isInteger()
    3. Number.isNaN()
    4. Number.isSafeInteger()
    5. Number.parseFloat()
    6. Number.parseInt()
    1. Number.EPSILON
    2. Number.MAX_SAFE_INTEGER
    3. Number.MAX_VALUE
    4. Number.MIN_SAFE_INTEGER
    5. Number.MIN_VALUE
    6. Number.NaN
    7. Number.NEGATIVE_INFINITY
    8. Number.POSITIVE_INFINITY
    1. Number.prototype.toExponential()
    2. Number.prototype.toFixed()
    3. Number.prototype.toLocaleString()
    4. Number.prototype.toPrecision()
    5. Number.prototype.toString()
    6. Number.prototype.valueOf()
  8. Object/Function
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    5. Function.prototype[Symbol.hasInstance]()
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    5. Object.prototype.hasOwnProperty()
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    8. Object.prototype.toLocaleString()
    9. Object.prototype.toString()
    10. Object.prototype.valueOf()
    1. Object.prototype.__proto__
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