How to make a .replace loop in javascript?

Question

I am currently trying to make a .replace function loop in javascript. What I am trying to do is replace a random character with a hyphen, but the part that I am struggling with is how to make it loop the replacing of the character to hyphen. Here is the code that I have so far:

 var randHold;
 var randomWord;
 var randLetHold;
 var dispWord;
 var repLetHold;
 var myWords = new Array("Spectrometer", "Bandwagonjghvyjh", "jvjyvyvilvyjlvyv", 
 "fruitjjyvtyvjv", "seventctcvtv", "weathertfhtcthc", 
 "undercfxdtfv"); // random letters to make words that have more than 10 letters
 function level() { 
 randHold = parseInt((Math.random() * 6) + 1);//code to randomly pick a word from the above array
 randomWord = myWords[randHold]; //code to call the random word from the array
 randLetHold = (Math.random() * randomWord.length);//code to randomly pick a character from the random word chosen
 repLetHold = randomWord.charAt(randLetHold);//code to call the random character
 for (i = 1; i <= 3; i++) //loop to replace three random characters with a hyphen 
 {
 dispWord = randomWord.replace(repLetHold," - ");//code to replace a random character with a hyphen
 document.write(dispWord);//But all this does is display the word(with ONE hypenated character)three times.
 }
 }

Answer 1

Your code actually seems fine, the main issue is that you're declaring your random variables outside of your for loop. Doing this will only generate them once for the entire loop. Try this instead:

var dispWord;
var myWords = new Array("Spectrometer", "Bandwagonjghvyjh", "jvjyvyvilvyjlvyv", 
 "fruitjjyvtyvjv", "seventctcvtv", "weathertfhtcthc", 
 "undercfxdtfv"); // random letters to make words that have more than 10 letters
function level() { 
 for (i = 1; i <= 3; i++) //loop to replace three random characters with a hyphen 
 {
 var randHold = parseInt((Math.random() * 6) + 1);//code to randomly pick a word from the above array
 var randomWord = myWords[randHold]; //code to call the random word from the array
 var randLetHold = (Math.random() * randomWord.length);//code to randomly pick a character from the random word chosen
 var repLetHold = randomWord.charAt(randLetHold);//code to call the random character
 dispWord = randomWord.replace(repLetHold," - ");//code to replace a random character with a hyphen
 document.write(dispWord);//But all this does is display the word(with ONE hypenated character)three times.
 }
}

Answer 2

For 3 random characters to be hyphenated in the word, you want something like this.

<div id="result"></div>
var myWords = ["Spectrometer", "Bandwagonjghvyjh", "jvjyvyvilvyjlvyv",
 "fruitjjyvtyvjv", "seventctcvtv", "weathertfhtcthc",
 "undercfxdtfv"]; // random letters to make words that have more than 10 letters
var randomWord;
var dispWord;
var repLetHold = [];
function uniqueCount(str) {
 var unique = [];
 Array.prototype.forEach.call(str, function (value) {
 if (unique.indexOf(value) === -1) {
 unique.push(value);
 }
 });
 return unique.length;
}
function level() {
 var randHold = Math.floor(Math.random() * myWords.length);
 dispWord = randomWord = myWords[randHold];
 if (uniqueCount(randomWord) > 2) {
 var count = 0,
 temp1,
 temp2;
 while (count < 3) {
 temp1 = Math.floor(Math.random() * dispWord.length);
 temp2 = dispWord.charAt(temp1);
 if (temp2 !== "-" && repLetHold.indexOf(temp2) === -1) {
 dispWord = dispWord.replace(new RegExp(temp2, "g"), "-");
 repLetHold[count] = temp2;
 count += 1;
 }
 }
 }
 document.getElementById("result").textContent = dispWord;
}
level();
console.log(randomWord, repLetHold);

on jsfiddle

• Justin Morgan: This will replace an entire word with a hyphen. He wants to replace three single characters.
• Justin Morgan: Downvotes are what you're supposed to do for incorrect answers. It draws the answerer's attention to the mistake, and can be removed once the mistake is corrected. And I did check your jsFiddle before I voted. See for yourself.
• Justin Morgan: Your original form had var array = randomWord.split(' ');. That will cause entire words to be replaced. Either way, it looks correct now, so I'll remove the downvote.
• Xotic750: I don't think you'll find it did, stackoverflow.com/posts/16121954/revisions
• user2261185: I see what you did and it works perfectly, but I want the function to work specifically with the loop. Meaning I want the replace function/code to loop 3 times, so I want three characters in the word to be hypenated and not just one or two. But thank you very much Xotic750 for taking the time to answer my question.

Answer 3

If you use a regular expression, you can replace all instances at once with the g (global) flag. For example:

var str = "this is a mass Spectrometer, which is a Spectrometer to detect the spectra of different masses";
var replaced = str.replace(/Spectometer/g, 'something');
// "this is a mass something, which is a something to detect the spectra of different masses";

Just keep in mind that some characters must be escaped inside regular expressions.

Answer 4

http://jsfiddle.net/zt8mp/

If i got the question right:

randomWord.replace(new RegExp(repLetHold,'g')," - ")

replaces all occurences of repLetHold (as long as it is not made of special regex characters)