【PHP】【javascript】三項演算子の入れ子 switch文が不要になる？

コード

<?php
$test = 1;
echo ($test === 2 ? '○' : ($test === 1 ? '◎' : '×') );

echo ($test === 2 ? '○' 
   : ($test === 1 ? '◎' 
   : '×'
));

<?php
$test = 3;
echo ($test === 2 ? '○' 
   : ($test === 1 ? '◎' 
   : ($test === 3 ? 'a' 
   : 'b'
)));


$test = 77;
echo ($test === 2 ? '○' 
   : ($test === 1 ? '◎' 
   : ($test === 3 ? 'a' 
   : ($test === 4 ? 'c' 
   : 'b'
))));

javascript

process.stdin.resume();
process.stdin.setEncoding('utf8');
test = 1;
console.log(test === 2 ? '○' : (test === 1 ? '◎' : '×') );

結果

◎

javascript 入れ子

process.stdin.resume();
process.stdin.setEncoding('utf8');
let x = 5;

let a = x < 10 ? 1
      : x < 20 ? 2
      : x < 30 ? 3
      : 4;
      
console.log(a);

結果

1