Пробелы в JavaScript

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function towerBuilder(nFloors) { 
    let myString = ""; 
    for (let i = 1; i <= nFloors; i++) { 
        let q = i * 2 - 1; 
        let blankSpaceQuanity = nFloors - i; 
        let blankSpace = ""; 
        for (let k = 0; k < blankSpaceQuanity; k++) { 
            blankSpace += "_"; 
        } 
        myString += blankSpace; 
        for (let j = 1; j <= q; j++) { 
             
            myString += "*"; 
             
        } 
        myString += blankSpace; 
        myString += "<br>"; 
         
    } 
    return myString;  
} 
document.write(towerBuilder(5));