Rhino_01 - untersucht Datentyp-Konvertierungen

"Rhino_01" untersucht implizite und explizite Typ-Konvertierungen zwischen den verschiedenen, von JavaScript unterstützten Datentypen. Der Quelltext ist äußerst einfach und bedarf keiner besonderen Erläuterung.

Das Programm wird ohne Angabe von Kommandozeilen-Argumenten aufgerufen

  java Rhino Rhino_01.js

und liefert folgende Ausgabe:

  Rhino_01 - investigates implicit and explicit type conversions in Rhino

   - a Boolean value is printed as true or false
   - a Number  value is printed as 1 or 0.001, e.g.

   - to investigate the latter a little further:
     - 1E-1 is written as 0.1
     - 1E-2 is written as 0.01
     - 1E-3 is written as 0.001
     - 1E-4 is written as 0.0001
     - 1E-5 is written as 0.00001
     - 1E-6 is written as 0.0000010000000000000002
     - 1E-7 is written as 1.0000000000000002e-7
     - 1E-8 is written as 1.0000000000000002e-8
     - 1E-9 is written as 1.0000000000000003e-9

   - "adding" true  to 1 yields 2
   - "adding" false to 1 yields 1

   - parseInt("10101010", 2) yields 170
   - parseInt("-10101010", 2) yields -170
   - parseInt("123", 2) yields 1
   - parseInt("-12345", 10) yields -12345
   - parseInt("-abcd", 16) yields -43981
   - parseInt("0xABCD", 16) yields 43981

   - parseFloat("-1.2345") yields -1.2345
   - parseFloat("+123e-45") yields 1.23e-43
   - parseFloat("0.0000000000000000000000000000000000000001") yields 1e-40
   - parseFloat("-1.2345abc") yields -1.2345

   - toString(Number.MAX_VALUE) yields 1.7976931348623157e+308
   - toString(Number.MIN_VALUE) yields 5e-324
   - toString(Number.NaN) yields NaN
   - toString(Number.NEGATIVE_INFINITY) yields -Infinity
   - toString(Number.POSITIVE_INFINITY) yields Infinity
   - toString(+0) yields 0
   - toString(-0) yields 0

   - (123456).toExponential(3) yields 1.235e+5
   - (-123.456e-6).toExponential(3) yields -1.235e-4
   - (-123.456e-6).toExponential(20) yields -1.234560000000000051878e-4
   - (Number.NaN).toExponential(3) yields NaN
   - (Number.NEGATIVE_INFINITY).toExponential(3) yields -Infinity
   - (Number.POSITIVE_INFINITY).toExponential(3) yields Infinity

   - (123456).toFixed(3) yields 123456.000
   - (-123.456e-6).toFixed(3) yields -0.000
   - (-123.456e-6).toFixed(20) yields -0.000123456000000000001
   - (Number.NaN).toFixed(3) yields NaN
   - (Number.NEGATIVE_INFINITY).toFixed(3) yields -Infinity
   - (Number.POSITIVE_INFINITY).toFixed(3) yields Infinity

   - (123456).toPrecision(3) yields 1.23e+5
   - (-123.456e-6).toPrecision(3) yields -0.000123
   - (-123.456e-6).toPrecision(20) yields -0.000123456000000000005189
   - (Number.NaN).toPrecision(3) yields NaN
   - (Number.NEGATIVE_INFINITY).toPrecision(3) yields -Infinity
   - (Number.POSITIVE_INFINITY).toPrecision(3) yields Infinity

Dieses Ergebnis wird am besten zusammen mit dem Quelltext des Skriptes analysiert - wer sich mit JavaScript ein wenig auskennt, wird wohl keine Überraschungen erleben.

Quelltexte

Das hier vorgestellte Skript ist im Quelltext verfügbar:

• Rhino_01.js