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' Aggiungere numeri e stringhe
' AVVERTIMENTO !! ' JavaScript utilizza l'operatore + sia per l'aggiunta che per la concatenazione. ' I numeri sono aggiunti. Le stringhe sono concatenate. ' var x = 10; ' var y = 20; ' var z = x + y; // z will be 30 (a number) 'Se aggiungi due stringhe, il risultato sara' una concatenazione di stringhe: 'Esempio 'var x = "10"; 'var y = "20"; 'var z = x + y; // z will be 1020 (a string) https://www.w3schools.com/js/tryit.asp?filename=tryjs_numbers_add_strings1 <!DOCTYPE html> <html> <body> <h2>JavaScript Numbers</h2> <p>If you add two numeric strings, the result will be a concatenated string:</p> <p id="demo"></p> <script> var x = "10"; var y = "20"; var z = x + y; document.getElementById("demo").innerHTML = z; </script> </body> </html> ' oppure https://www.w3schools.com/js/tryit.asp?filename=tryjs_numbers_add <!DOCTYPE html> <html> <body> <h2>JavaScript Numbers</h2> <p>If you add two numbers, the result will be a number:</p> <p id="demo"></p> <script> var x = 10; var y = 20; var z = x + y; document.getElementById("demo").innerHTML = z; </script> </body> </html> ' oppure https://www.w3schools.com/js/tryit.asp?filename=tryjs_numbers_add_strings5 ' The result is: 1020 <!DOCTYPE html> <html> <body> <h2>JavaScript Numbers</h2> <p>If you add a numeric string and a number, the result will be a concatenated string:</p> <p id="demo"></p> <script> var x = "10"; var y = 20; document.getElementById("demo").innerHTML = "The result is: " + x + y; </script> </body> </html> ' Oppure https://www.w3schools.com/js/tryit.asp?filename=tryjs_numbers_add_strings4 ' A common mistake is to expect this result to be 102030: ' 3030 <!DOCTYPE html> <html> <body> <h2>JavaScript Numbers</h2> <p>A common mistake is to expect this result to be 102030:</p> <p id="demo"></p> <script> var x = 10; var y = 20; var z = "30"; var result = x + y + z; document.getElementById("demo").innerHTML = result; </script> </body> </html> ' JavaScript provera' a convertire stringhe in numeri in tutte le operazioni numeriche: ' Questo funzionera': 'var x = "100"; 'var y = "10"; 'var z = x / y; // z will be 10 'Questo funzionera' anche: 'var x = "100"; 'var y = "10"; 'var z = x * y; // z will be 1000 'E questo funzionera': 'var x = "100"; 'var y = "10"; 'var z = x - y; // z will be 90 'Ma questo non funzionera': 'var x = "100"; 'var y = "10"; 'var z = x + y; // z will not be 110 (It will be 10010) |