搜索和替换字符串而不使用正则表达式而是循环，如何一次替换多个单词？

Question

I found a way to do string search and replace without using Regex but when I want to replace more than one instance it does it one out at time instead of all instances at the same time. How can I get the loop to work?

 'use strict' function main() { document.addEventListener('DOMContentLoaded', function() { document.getElementById('replace').addEventListener('click', replace); document.getElementById('replaceAll').addEventListener('click', replaceAll); }); } function replace(evnt) { evnt.preventDefault() let userText = document.getElementById('input').value; let search = document.getElementById('search').value; let replaceText = document.getElementById('replaceText').value; let caseSensitive = document.getElementById('case').checked; document.getElementById('input').value = userText.replace(search, replaceText); } function replaceAll(evnt) { evnt.preventDefault(); let userText = document.getElementById('input').value; let search = document.getElementById('search').value; let replaceText = document.getElementById('replaceText').value; for (let r = 0; r < userText.indexOf(search); r++) { document.getElementById('input').value = userText.replace(search, replaceText); console.log(r); } }

 <form id="form"> <div> <textarea id="input" row="10" cols="50" placeholder="Enter text here"></textarea> </div> <div> <input type="text" id="search" name="search"> <input type="text" id="replaceText" name="replacebox"> </div> <div> <input type="checkbox" id="case" name="case sensitivity" /> <label for="uppercase">case sensitivity</label> </div> <div> <button type="submit" id="replace">Replace</button> </div> <div> <button type="submit" id="replaceAll">Replace all</button> </div> </form>

Answer 1

In

for(let r = 0; r < userText.indexOf(search);r++) {
    document.getElementById('input').value = userText.replace(search, replaceText);
}

On every iteration, you're taking the userText string and replacing one substring inside it. You're not taking the replaced string from the prior iteration; you're taking the original string, so in the end, no more than one replacement, at most, will have been made.

Reassign a variable instead, perhaps userText , then assign to the input after the loop is done:

for(let r = 0; r < userText.indexOf(search);r++) {
    userText = userText.replace(search, replaceText);
}
document.getElementById('input').value = userText;

Could also use .includes , it's more intuitive:

while (userText.includes(search)) {
  userText = userText.replace(search, replaceText);
}

 'use strict' function main() { document.addEventListener('DOMContentLoaded', function() { document.getElementById('replace').addEventListener('click', replace); document.getElementById('replaceAll').addEventListener('click', replaceAll); }); } function replace(evnt) { evnt.preventDefault() let userText = document.getElementById('input').value; let search = document.getElementById('search').value; let replaceText = document.getElementById('replaceText').value; let caseSensitive = document.getElementById('case').checked; document.getElementById('input').value = userText.replace(search, replaceText); } function replaceAll(evnt) { evnt.preventDefault(); let userText = document.getElementById('input').value; let replaceText = document.getElementById('replaceText').value; while (userText.includes(search.value)) { userText = userText.replace(search.value, replaceText); } input.value = userText; } const [repButton, repAllButton] = document.querySelectorAll('button'); repButton.onclick = replace; repAllButton.onclick = replaceAll;

 <form id="form"> <div> <textarea id="input" row="10" cols="50" placeholder="Enter text here">abcabc</textarea> </div> <div> <input type="text" id="search" name="search" value="abc"> <input type="text" id="replaceText" name="replacebox" value="123"> </div> <div> <input type="checkbox" id="case" name="case sensitivity" /> <label for="uppercase">case sensitivity</label> </div> <div> <button type="submit" id="replace">Replace</button> </div> <div> <button type="submit" id="replaceAll">Replace all</button> </div> </form>