function encode(arr){ let encodedStr=''; for(let x of arr){ encodedStr=encodedStr.concat(x.length,x); } console.log(encodedStr); return encodedStr; } function decode(str){ const arr=[]; let wordLength=str[0]; for(let x=1; x<str.length; x++){ let word='' while(wordLength--){ word+=str[x++]; } arr.push(word); wordLength=str[x] } console.log(arr) return arr; } decode(encode(["p","oil","p9095o","123455"]));