Bits of .NET

const theName = "Vincent van Gogh";

function hideWord(word) {
    if (word.length < 2) return word;
    return word.substring(0, 1) + '*'.repeat(word.length-1);
}

console.log(theName.split(" ").map(hideWord).join(" "));

OUTPUT:
V****** v** G***

You could also wrap the whole lot in a function if you wanted to be able to call it from multiple places and avoid redefining it.

function hideWords(allTheWords) {
    return allTheWords.split(" ").map(hideWord).join(" ");
}

console.log(hideWords(theName));