JavaScipt练习<filter()>

给出key 和value对应的一组数组：[ [ "foo", "[e-mail]" ], [ "bar_", "[e-mail]" ] ,...]，找出其中key以“_”结尾的所有项，并返回数组

function searchNames( logins ){function findEndWith_(item){return (item[0].lastIndexOf('_')===item[0].length-1);}  return logins.filter(findEndWith_);}

function searchNames( logins ){  return logins.filter(function (login) { return login[0].slice(-1) === '_' });}

function searchNames( logins ){  return logins.filter(function(arr){    return arr[0].match(/_$/);});}

function searchNames( logins ){  return logins.filter(function(user) {    return user[0].charAt(user[0].length - 1) === '_';  });}