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Created Aug 3, 2019
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JavaScript Text Counter
<!DOCTYPE html>
<html lang="ja">
<meta charset="utf-8">
<link rel="stylesheet" href="" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
.container {
width: 500px;
margin-top: 100px;
font-size: 18px;
#count1, #count2 {
color: grey;
<div class="container">
<div class="form-group">
<textarea class="form-control" rows="5" onkeyup="count_up(this);"></textarea>
<span id="count1" class="float-right">0</span>
<div class="form-group">
<textarea class="form-control" rows="5" onkeyup="count_down(this);"></textarea>
<span id="count2" class="float-right">30</span>
function count_up(obj) {
document.getElementById('count1').innerHTML = obj.value.length;
function count_down(obj) {
var element = document.getElementById('count2');
element.innerHTML = 30 - obj.value.length;
if (30 - obj.value.length < 0) { = 'red';
} else { = 'grey';
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