<pre class="shiki github-dark shaku"><code>// This is a JavaScript coding problem from BFE.dev /** * @param {string[][]} message * @return {string} */function decode(msg) { // your code here if (!msg || !msg.length || !msg[0].length) return ''; const m = msg.length, n = msg[0].length; let i = 0, j = 0; let str = ''; let dir = 1; // 1: down-right, -1: up-right while (true) { str += msg[i][j]; let ni = i + dir, nj = j + 1; if (ni &gt;= 0 &amp;&amp; ni &lt; m &amp;&amp; nj &lt; n) { i = ni; j = nj; } else { // try to switch direction dir *= -1; ni = i + dir; nj = j + 1; if (ni &gt;= 0 &amp;&amp; ni &lt; m &amp;&amp; nj &lt; n) { i = ni; j = nj; } else { break; } } } return str;}</code></pre>