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<body>
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<p>1.797693134862315E+308 是浮点数的极限。</p>
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<p>请点击按钮来亲自查看。</p>
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<button onclick="myFunction()">试一试</button>
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<p id="demo"></p>
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<script>
function myFunction() {  
  document.getElementById("demo").innerHTML = 
  1.7976931348623157E+10308 + "<br>" +  -1.7976931348623157E+10308;
}
</script>
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</body>
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