NaN在这段代码中允许数字和字母的组合。

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英文:

NaN is allowing a combination of numbers and letters in this code

问题

为什么NaN允许我的代码中组合数字和字母？

  1. let gameIsStarted = false;
  2. let guesses = [];
  4. const startButton = document.getElementById('startButton');
  6. startButton.addEventListener('click', function() {
  7.   gameIsStarted = !gameIsStarted;
  9.   if (gameIsStarted) {
  10.     let n = 0;
  11.     while (n <= 0) {
  12.       n = Math.round(parseFloat(prompt('您已开始游戏。您希望猜测的最大数字是多少？')));
  13.       if (isNaN(n)) {
  14.         alert('那不是一个数字！请输入一个数字。');
  15.         n = 0;
  16.       } else if (n < 1) {
  17.         alert('请输入1或更高的数字。');
  18.         n = 0;
  19.       }
  20.     }
  22.     let secretNum = secretNumber(n);
  23.     guess(secretNum);
  25.     function secretNumber(n) {
  26.       return Math.floor(Math.random() * n) + 1;
  27.     }
  29.     function userGuess() {
  30.       let guessValue = parseInt(prompt('您认为这个数字是多少？'));
  31.       guessValue = Math.round(guessValue);
  32.       return guessValue;
  33.     }
  35.     function guess(secretNum) {
  36.       let userGuessValue = userGuess();
  37.       while (userGuessValue !== secretNum) {
  38.         switch (true) {
  39.           case isNaN(userGuessValue):
  40.             alert('那不是一个数字！');
  41.             userGuessValue = userGuess();
  42.             break;
  43.           case userGuessValue <= 0:
  44.             alert('那个数字太低了。请选择至少为1的数字。');
  45.             userGuessValue = userGuess();
  46.             break;
  47.           case userGuessValue > n:
  48.             alert('那个数字不在范围内，请重试。');
  49.             userGuessValue = userGuess();
  50.             break;
  51.           case userGuessValue > secretNum:
  52.             alert('不，尝试一个较低的数字。');
  53.             userGuessValue = userGuess();
  54.             break;
  55.           case userGuessValue < secretNum:
  56.             alert('不，尝试一个更高的数字。');
  57.             userGuessValue = userGuess();
  58.             break;
  59.         }
  60.       }
  61.       alert('你猜对了！');
  62.     }
  63.   }
  64.   gameIsStarted = false;
  65. });

我已经尝试使用元字符，问了我认识的每个人，但它仍然允许像13a或17w这样的输入。当我查看NaN的文档时，它在那里工作，所以为什么在我的代码中没有实现？

英文:

Why is NaN allowing a combination of numbers and letters in my code?

  1. let gameIsStarted = false;
  2. let guesses = [];
  3. const startButton = document.getElementById(&#39;startButton&#39;);
  4. startButton.addEventListener(&#39;click&#39;, function() {
  5. gameIsStarted = !gameIsStarted;
  6. if (gameIsStarted) {
  7. let n = 0;
  8. while (n &lt;= 0) {
  9. n = Math.round(parseFloat(prompt(&#39;You have begun to play. What is the highest number you wish to be able to guess?&#39;)));
  10. if (isNaN(n)) {
  11. alert(&#39;That is not a number! Please enter a number.&#39;);
  12. n = 0;
  13. } else if (n &lt; 1) {
  14. alert(&#39;Please enter a number 1 and above.&#39;);
  15. n = 0;
  16. }
  17. }
  18. let secretNum = secretNumber(n);
  19. guess(secretNum);
  20. function secretNumber(n) {
  21. return Math.floor(Math.random() * n) + 1;
  22. }
  23. function userGuess() {
  24. let guessValue = parseInt(prompt(&#39;What do you think the number is?&#39;));
  25. guessValue = Math.round(guessValue);
  26. return guessValue;
  27. }
  28. function guess(secretNum) {
  29. let userGuessValue = userGuess();
  30. while (userGuessValue !== secretNum) {
  31. switch (true) {
  32. case isNaN(userGuessValue):
  33. alert(&#39;That is not a number!&#39;);
  34. userGuessValue = userGuess();
  35. break;
  36. case userGuessValue &lt;= 0:
  37. alert(&#39;That number is too low. Pick a number that is at least 1.&#39;);
  38. userGuessValue = userGuess();
  39. break;
  40. case userGuessValue &gt; n:
  41. alert(&#39;That number is not in range, try again.&#39;);
  42. userGuessValue = userGuess();
  43. break;
  44. case userGuessValue &gt; secretNum:
  45. alert(&#39;No, try a lower number.&#39;);
  46. userGuessValue = userGuess();
  47. break;
  48. case userGuessValue &lt; secretNum:
  49. alert(&#39;No, try a higher number.&#39;);
  50. userGuessValue = userGuess();
  51. break;
  52. }
  53. }
  54. alert(&#39;You got it!&#39;);
  55. }
  56. }
  57. gameIsStarted = false;
  58. });

I have tried to use Metacharacters, I have asked everyone I know, but this will allow things like 13a or 17w. When I looked up the documentation on NaN, it worked there, so why is it not implementing in my code?

答案1

得分: 0

这将允许类似于13a或17w的情况。

罪魁祸首是parseInt和parseFloat。它们允许数字后面跟着其他字符。

要严格验证输入，请使用一元number coercion。

然后，根据您需要的数字类型执行其他检查。

函数 testNumber（值）{
    console.log（'Value:'，value）;
    console.log（'> integer OR fractional:'，Number.isFinite（value））;
    console.log（'> integer:'，Number.isInteger（value））;
    console.log（'> fractional:'，Number.isFinite（value）&& value！= Math.floor（value））;
}

testNumber（+'777$#@!*'）;
testNumber（+'777.888'）;
testNumber（+'1234'）;

英文:

> this will allow things like 13a or 17w

The culprits are parseInt and parseFloat. They allow digits to be followed by other characters.

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

  1. console.log(parseInt(&#39;777$#@!*&#39;)); // 777
  2. console.log(parseFloat(&#39;123.56abcd&#39;)); // 123.56

<!-- end snippet -->

To validate the input strictly, use unary number coersion.

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

  1. console.log(+&#39;777$#@!*&#39;); // NaN
  2. console.log(+&#39;777&#39;); // 777
  3. console.log(+&#39;123.56abcd&#39;); // NaN
  4. console.log(+&#39;123.56&#39;); // 123.56

<!-- end snippet -->

Then you can perform other checks depending on what sort of number you need.

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

  1. function testNumber (value) {
  2. console.log(&#39;Value:&#39;, value);
  3. console.log(&#39;&gt; integer OR fractional:&#39;, Number.isFinite(value));
  4. console.log(&#39;&gt; integer:&#39;, Number.isInteger(value));
  5. console.log(&#39;&gt; fractional:&#39;, Number.isFinite(value) &amp;&amp; value != Math.floor(value));
  6. }
  7. testNumber(+&#39;777$#@!*&#39;);
  8. testNumber(+&#39;777.888&#39;);
  9. testNumber(+&#39;1234&#39;);

<!-- end snippet -->

huangapple
  • 本文由 发表于 2023年6月2日 05:21:15
  • 转载请务必保留本文链接：https://go.coder-hub.com/76385789.html
  • javascript
  • nan
  • numbers
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