Question

我的过渡不起作用，我不明白为什么。

HTML代码

<!-- The user can select here the language -->
<select name="language" id="language" onChange="ChangeLanguage()">
    <option value=" " selected/> 
    <option value="Basic"/>Basic
    <option value="C/C++" />C/C++
</select>

<div id="PartieCPP"> <!-- This <div> disappear when the user choose "Basic" -->
    ...
</div>

<div id="PartieBAS"> <!-- This <div> disappear when the user choose "C/C++" -->
    ...
</div>

JAVASCRIPT代码

function ChangeLanguage() //this function is called when the user change the selected language
{
    var choise =  document.getElementById("language").options[document.getElementById("language").selectedIndex].value; 

    if ( choise == "C/C++")
    {
        document.getElementById("PartieCPP").style.height = "auto"; //"PartieCPP" appear
        document.getElementById("PartieBAS").style.height = "0px"; //"PartieBAS" disappear
    }
    else if (choise == "Basic")
    {
        document.getElementById("PartieCPP").style.height = "0px"; //"PartieCPP" disappear
        document.getElementById("PartieBAS").style.height = "auto"; //"PartieBAS" appear
    }
    else
    {
        document.getElementById("PartieBAS").style.height = "0px"; //"PartieBAS" disappear
        document.getElementById("PartieCPP").style.height = "0px"; //"PartieCPP" disappear
    }
}

CSS代码

#PartieCPP, #PartieBAS
{
    height : 0px;
    overflow : hidden;

    -webkit-transition: height 2s;
    -moz-transition: height 2s;
    transition: height 2s;
}

这段代码工作正常，但没有过渡，有人可以向我解释我做错了什么吗？

（我在Chrome和Firefox上试过）

Answer 1

您需要输入像素值才能获得转换。您无法从“0px”转换为“自动”。

这是link to a demo

这个JavaScript似乎可以解决问题：

function ChangeLanguage() //this function is called when the user change the selected language
{
    var choise =  document.getElementById("language").options[document.getElementById("language").selectedIndex].value; 

    if ( choise == "C/C++")
    {
        document.getElementById("PartieCPP").style.height = "50px"; //"PartieCPP" appear
        document.getElementById("PartieBAS").style.height = "0px"; //"PartieBAS" disappear
    }
    else if (choise == "Basic")
    {
        document.getElementById("PartieCPP").style.height = "0px"; //"PartieCPP" disappear
        document.getElementById("PartieBAS").style.height = "50px"; //"PartieBAS" appear
    }
    else
    {
        document.getElementById("PartieBAS").style.height = "0px"; //"PartieBAS" disappear
        document.getElementById("PartieCPP").style.height = "0px"; //"PartieCPP" disappear
    }
}

CSS3过渡不起作用

1 个答案: