<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> var a=5; var b='5'; alert(a==b);//true 先转换类型再比较 alert(a===b);//false 不转换类型直接比较 </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> var a='12'; var b='5'; alert(a+b);//125 字符串连接 数字相加 alert(a-b);//7 数字相减 </script> </body> </html>
闭包：子函数可以使用父函数的局部变量