index.html
<!DOCTYPE html><html><head><linkrel="stylesheet"href="./index.css"></head><body><divclass="a"><buttontype="button"class="toggle button">aaa</button><divclass="area">
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</div></div><divclass="a"><buttontype="button"class="toggle button">aaa</button><divclass="area">
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</div></div><divclass="a"><buttontype="button"class="toggle button">aaa</button><divclass="area">
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</div></div><script src="https://code.jquery.com/jquery-3.3.1.js"></script><script>$(function(){varselect=document.getElementsByClassName("area");varbutton=document.getElementsByClassName("button");varheight=[];vardur=[];for(vari=0;i<select.length;i++){console.log(select[i]);height[i]=$(select[i]).height();dur[i]=height[i]/0.1;/*0.1は任意の速度*/$(select[i]).css({display:"none"})$(button[i]).addClass("button"+i);};vartoggleFunction=function(button,index){$(button).click(function(){$(this).next().slideToggle(dur[index]);});};toggleFunction(".button0",0);toggleFunction(".button1",1);toggleFunction(".button2",2);});</script></body></html>index.css
.a{width:100px;display:block;}.a>button{width:100%;}.a>.area{width:100%;word-break:break-all;}