Javascript语句满足所有可能出错的条件

Question

这个代码符合所有条件，请有人告诉我我哪里出错了，我已经检查过了，我看不出代码有什么问题。为什么所有的条件都满足了。

<script>
$( document ).ready(function() {
    var style = $('#el_teams_TeamFormation span').html(); 
    alert (style);
         if (style = "4-4-2")
          { 
            document.getElementById('footballpitch1').style.display = "none";
            document.getElementById('footballpitch2').style.display = "none";
            document.getElementById('footballpitch3').style.display = "none";
            document.getElementById('footballpitch4').style.display = "none";
            document.getElementById('footballpitch1').style.display = "block";
         }
         if (style = "3-4-3")
          {
            document.getElementById('footballpitch1').style.display = "none";
            document.getElementById('footballpitch2').style.display = "none";
            document.getElementById('footballpitch3').style.display = "none";
            document.getElementById('footballpitch4').style.display = "none";
            document.getElementById('footballpitch2').style.display = "block";
         } 
         if (style = "3-5-2") {
            document.getElementById('footballpitch1').style.display = "none";
            document.getElementById('footballpitch2').style.display = "none";
            document.getElementById('footballpitch3').style.display = "none";
            document.getElementById('footballpitch4').style.display = "none";
            document.getElementById('footballpitch3').style.display = "block";
         }
         if (style = "4-5-1") {
            document.getElementById('footballpitch1').style.display = "none";
            document.getElementById('footballpitch2').style.display = "none";
            document.getElementById('footballpitch3').style.display = "none";
            document.getElementById('footballpitch4').style.display = "none";
            document.getElementById('footballpitch4').style.display = "block";
         }
});

​

Answer 1

有必要熟悉不同类型的比较操作符：

Operators

简单地说，单(=)、双(==)和三(===)等于符号对JavaScript来说意味着不同的东西。

单个=是赋值操作符，因此在每个if语句中，您实际上都要求脚本将"4-4-2“(以此类推)的值赋值给变量style，而不是比较这两个值。

如果您使用== (带有类型强制)或=== (没有强制)，那么您的代码应该可以正常工作。

Answer 2

if (style == "4-4-2")
          { 
            document.getElementById('footballpitch1').style.display = "none";
            document.getElementById('footballpitch2').style.display = "none";
            document.getElementById('footballpitch3').style.display = "none";
            document.getElementById('footballpitch4').style.display = "none";
            document.getElementById('footballpitch1').style.display = "block";
         }
         if (style == "3-4-3")
          {
            document.getElementById('footballpitch1').style.display = "none";
            document.getElementById('footballpitch2').style.display = "none";
            document.getElementById('footballpitch3').style.display = "none";
            document.getElementById('footballpitch4').style.display = "none";
            document.getElementById('footballpitch2').style.display = "block";
         } 
         if (style == "3-5-2") {
            document.getElementById('footballpitch1').style.display = "none";
            document.getElementById('footballpitch2').style.display = "none";
            document.getElementById('footballpitch3').style.display = "none";
            document.getElementById('footballpitch4').style.display = "none";
            document.getElementById('footballpitch3').style.display = "block";
         }
         if (style == "4-5-1") {
            document.getElementById('footballpitch1').style.display = "none";
            document.getElementById('footballpitch2').style.display = "none";
            document.getElementById('footballpitch3').style.display = "none";
            document.getElementById('footballpitch4').style.display = "none";
            document.getElementById('footballpitch4').style.display = "block";
         }