JS返回数组种类和个数(面试常问)
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title></title> <script type="text/javascript"> var a = ["aaa", "aaa", "aaa", "aaa", 'a', 'aaaaaa', '哈哈哈', 'aaaaaa', 'bbbb']; var b = {}; var c = {}; for(var i = 0; i < a.length; i++) { if(a[i] in b) { b[a[i]]++; } else { b[a[i]] = 1; } } console.log(b); for(var j = 0; j < a.length; j++) { if(c[a[j]]) { c[a[j]]++; } else { c[a[j]] = 1; } } console.log(c); </script> </head> <body> </body> </html>