两个左右V形符号不显示,它可以工作,但由于某种原因它显示了一个方框.当我点击glyhicons的位置时,我可以滚动浏览图片,所以不正确的是左右箭头通常预期的字形的外观没有显示？
<!DOCTYPE html>
<html>
<head>
<title>Student Association</title>
<link rel="stylesheet" href="css/bootstrap.min.css">
</head>
<body>
<div class="carousel slide" data-ride="carousel" id="carousel-ex">
<ol class="carousel-indicators">
<li class="active" data-slide-to="0" data-target="#carousel-ex"></li>
<li data-slide-to="1" data-target="#carousel-ex"></li>
<li data-slide-to="2" data-target="#carousel-ex"></li>
<li data-slide-to="3" data-target="#carousel-ex"></li>
<li data-slide-to="4" data-target="#carousel-ex"></li>
<li data-slide-to="5" data-target="#carousel-ex"></li>
</ol>
<div class="carousel-inner">
<div class="item active"><img alt="abuja" class="img-responsive" id=
"afCountries" src="img/african-countries/abuja-nigeria.jpg">
<div class="carousel-caption">
<h3>Abuja, Nigeria</h3>
</div>
</div>
<div class="item"><img alt="accra" class="img-responsive" id="afCountries" src=
"img/african-countries/accra-ghana.jpg">
<div class="carousel-caption">
<h3>Accra, Ghana</h3>
</div>
</div>
<div class="item"><img alt="kigali" class="img-responsive" id="afCountries"
src="img/african-countries/kigali-rwanda.jpg">
<div class="carousel-caption">
<h3>Kigali, Rwanda</h3>
</div>
</div> …function negate(func) {
return function(x) {
return !func(x);
};
}
var isNotNaN = negate(isNaN);
show(isNotNaN(NaN));
这是我正在阅读的一本javascript书.func用作函数的参数x和前面的否定符号.怎么会？