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Question

如何使用Javascript预设表格中的值？

<u><h1>Rabbits vs Foxes Population Model</h1></u> 
    <form name = "Rabbits"> 
    <table border = "3"> 
    <tr><td>No. of Rabbits</td><td><center><input type="number" id="no_rabbits" /></center></td></tr> 
    <tr><td>Death Rates</td><td><center><input type="number" id="death" /></center></td></tr> 
    <tr><td>Birth Rates</td><td><center><input type="number" id="birth" /></center></td></tr> 
    <tr><td>No. of Foxes</td><td><center><input type="number" id="foxes" /></center></td></tr> 
    <tr><td>Rabbit Conditions</td><td> Normal <input type="radio" name="condition" value="normal"> Cold <input type="radio" name="condition" value="cold"> Fires <input type="radio" name="condition" value="fires">Excellent <input type="radio" name="condition" value="excellent"></td></tr> 
    <tr><td> Graph the Rabbits</td><td><input type="checkbox" name="graph" value="answer"></td></tr> 
    <tr><td><button type = "button" onclick="addyear()"> One Year Passes </button></td><td> </td></tr> 
    </table> 
    </form> 

Answer 1

声明输入时您可以设置的值（例如：<input type="number" id="no_rabbits" value="23"/>）或用JavaScript做到这一点和目标使用每个ID的输入和简单地设置该值。请注意，我也改变了你的h1结构 - 对于h1应用css规则要好得多，而不是h1的。不知道每个值是什么 - 只需设置为1 - 4就可以了。另外addYear函数没有声明，因此在点击时发生错误。我也删除了<center>标签 - 它们不再被支持，你应该使用CSS来为所需的td应用居中CSS规则。

另一件事 - 即使这些输入设置为type =“number”，它们仍然会返回一个字符串 - 因此您需要解析它们（使用parseInt或parseFloat）以获取计算的数字。

document.getElementById('no_rabbits').value="1"; 
 
document.getElementById('death').value="2"; 
 
document.getElementById('birth').value="3"; 
 
document.getElementById('foxes').value="4";

h1{text-decoration: underline}

<h1>Rabbits vs Foxes Population Model</h1> 
 
    <form name = "Rabbits"> 
 
    <table border = "3"> 
 
    <tr><td>No. of Rabbits</td><td><input type="number" id="no_rabbits" /></td></tr> 
 
    <tr><td>Death Rates</td><td><input type="number" id="death" /></td></tr> 
 
    <tr><td>Birth Rates</td><td><input type="number" id="birth" /></td></tr> 
 
    <tr><td>No. of Foxes</td><td><input type="number" id="foxes" /></td></tr> 
 
    <tr><td>Rabbit Conditions</td><td> Normal <input type="radio" name="condition" value="normal"> Cold <input type="radio" name="condition" value="cold"> Fires <input type="radio" name="condition" value="fires">Excellent <input type="radio" name="condition" value="excellent"></td></tr> 
 
    <tr><td> Graph the Rabbits</td><td><input type="checkbox" name="graph" value="answer"></td></tr> 
 
    <tr><td><button type = "button" onclick="addyear()"> One Year Passes </button></td><td> </td></tr> 
 
    </table> 
 
    </form>