JavaScript - 在数字输入之前打印奇数和偶数
[英]JavaScript - Print Odd & Even numbers preceding number input
问题描述
I am trying to print all odd & even numbers (in 2 different fields) up to the number entered by the user.
我正在尝试将所有奇数和偶数（在 2 个不同的字段中）打印到用户输入的数字。
I have everything down to validate the input (ensure it is a positive 2 digit number), and I can print a message if I remove the For loops visible in my code, but when it comes to print all odd & even numbers up to a certain number I am literally stuck for 2 days now.我有一切来验证输入（确保它是一个正的 2 位数字），如果我删除了代码中可见的 For 循环，我可以打印一条消息，但是当涉及到打印所有奇数和偶数时某个数字我现在真的被困了 2 天。
Could anyone please point me towards direction ?任何人都可以请指出我的方向吗？ I don't want all the codes, just telling me if I am completely wrong and should use another method would already help me, but at the moment I just can't get anywhere, and I can't find any similar question.我不想要所有的代码，只是告诉我是否完全错误并且应该使用另一种方法已经对我有所帮助，但目前我无处可去，也找不到任何类似的问题。
Here is my entire code so far (including my failing attempt to print odd & even numbers):到目前为止，这是我的全部代码（包括我尝试打印奇数和偶数失败）：
function myFunction() { var x, message; x = document.getElementById("positiveInteger").value; if (x == "") { alert("Input is empty. Please enter a positive 2 digit number."); } else if (isNaN(x)) { alert("Input is not a number. Please enter a positive 2 digit number."); } else if (x >= 1 && x <= 9) { alert("Input is too low. Please enter a positive 2 digit number."); } else if (x > 99) { alert("Input is too high. Please enter a positive 2 digit number."); } else if (x == 00) { alert("Input is not valid, 00 is not a positive number. Please enter a positive 2 digit number."); } else { for (i = 0; i < x; i + 2) { // This is my attempt to add 2 from 0 (hoping to get all even numbers) to each iteration until we reach the number input. message = document.getElementById("evenNumbers").innerHTML; } for (i = 1; i < x; i + 2) { // This is my attempt to add 2 from 1 (hoping to get all odd numbers) to each iteration until we reach the number input. message = document.getElementById("oddNumbers").innerHTML; } } }
<!DOCTYPE html> <html lang=en> <head> <meta charset="UTF-8"> <link type="text/css" rel="stylesheet" href=""> <style type="text/css"></style> <meta name="description" content="..." /> <meta name="keywords" content="" /> <title>Q2 - Two Digit Number</title> </head> <script> </script> <body> <h1>Welcome to C1 Assignment 2 - Question 2 !</h1> <p>Please enter a positive 2 digit number:</p> <input type="text" name="integer" id="positiveInteger"> <br><br> <button type="button" name="button" onclick="myFunction()">Submit</button> <br><br> <p id="oddNumbers"></p> <p id="evenNumbers"></p> </body> </html>
1 个解决方案
解决方案1
2 已采纳 2020-01-07 19:36:24
You have the following problems:您有以下问题：
You're not assigning to
innerHTML, you're reading from it.您没有分配给innerHTML，您正在阅读它。You're not incrementing
iduring the loop.你没有在循环期间增加i。i + 2should bei += 2.i + 2应该是i += 2。You need to concatenate all the numbers into the
messagestring before assigning it to theinnerHTMLof the output elements.您需要将所有数字连接到message字符串中，然后再将其分配给输出元素的innerHTML。
function myFunction() { var x, message; x = document.getElementById("positiveInteger").value; if (x == "") { alert("Input is empty. Please enter a positive 2 digit number."); } else if (isNaN(x)) { alert("Input is not a number. Please enter a positive 2 digit number."); } else if (x >= 1 && x <= 9) { alert("Input is too low. Please enter a positive 2 digit number."); } else if (x > 99) { alert("Input is too high. Please enter a positive 2 digit number."); } else if (x == 00) { alert("Input is not valid, 00 is not a positive number. Please enter a positive 2 digit number."); } else { message = ""; for (i = 0; i < x; i += 2) { message += i + " "; } document.getElementById("evenNumbers").innerHTML = message; message = ""; for (i = 1; i < x; i += 2) { message += i + " "; } document.getElementById("oddNumbers").innerHTML = message; } }
<h1>Welcome to C1 Assignment 2 - Question 2 !</h1> <p>Please enter a positive 2 digit number:</p> <input type="text" name="integer" id="positiveInteger"> <br><br> <button type="button" name="button" onclick="myFunction()">Submit</button> <br><br> Odd: <p id="oddNumbers"></p> Even: <p id="evenNumbers"></p>
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