<pre class="shiki github-dark shaku"><code>// This is a JavaScript coding problem from BFE.dev /** * @param {string[][]} message * @return {string} */function decode(message) { if(!message.length) return ''; const ops = {rows: message.length, cols:message[0].length}; let direction = 'down'; const messageArr= []; for(let i=0, j=0; (direction==='down'? i&lt;ops.rows:i&gt;0),j&lt;ops.cols; (direction==='down' ?i++:i--),j++){ if(message?.[i]?.[j]!==undefined){ messageArr.push(message[i][j]) } else if(j&lt;ops.cols &amp;&amp; direction==='down') { direction='up' i=i-2; messageArr.push(message[i][j]) } else if(j&lt;ops.cols &amp;&amp; direction==='up') { direction='down' i=i+2; messageArr.push(message[i][j]) } } return messageArr.join('');}</code></pre>