Simple map reduce

simple-map-reduce.ts

const arr : String[] =  ["B$u$i$ld", "$t$$h$e", "N$e$x$t", "E$$ra", "$$o$f$", "S$$of$t$wa$r$e", "De$$ve$l$op$me$n$t"];
function buildTheSentence(arr: String[]) : String {
    const result: String = arr
        .map((str: String) => (str.match(/[a-zA-Z]/gm) || []).join(''))
        .reduce((sentence: String, word : String) => sentence + " " + word )
    return result;    
}

console.log(buildTheSentence(arr))