<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>无标题文档</title> <script> /* 参数=JS的数据类型： 数字、字符串、布尔、函数、对象、未定义 */ fn2('妙味课堂'); function fn2(a){ alert(a.charAt(2)); } function fn4(){ alert(4); } function fn3( fn ){ fn(); } fn3( fn4 ); function fn3( fn ){ fn(100); } fn3( function ( a ){ alert(a); } );//a=100 fn5( window, document ); function fn5( w, d ){ w.onload = function (){ d.body.innerHTML = 123; }; } </script> </head> <body> </body> </html>
<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>无标题文档</title> <script> function fn1(a){ if( typeof a === 'number' && a === a ){//a === a,NaN也是数字类型，NaN不等于自己，这是排除NaN alert( a+20 ); } else if ( typeof a === 'string' ) { alert( a.charAt(2) ); } else if ( typeof a === 'function' ) { a(100);//alert(101) } } fn1(100); fn1('miaov'); fn1(function (arr){ alert(1+arr); }); </script> </head> <body> </body> </html>