String literal

let t = ["abcdefghi"];

let MyA = t[0].split("");


let v = MyA.reduce((p,n,i) => (i%3===0) ? (`
${p}

${n}`) : `${p} ${n}`);

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transposé !

const A = [
  [1,3,5],
  [2,4,6]
];

let At = A[0].map( (_,col) => A.map( (lig,_) =>lig[col]));

console.log(`|${A.join("|\n|")}| `) ;

console.log(`|${At.join("|\n|")}| `) ;