JSFiddle - React, Tailwind, and code Playground
HTML
<input type="text" id="input">
<span id="output"></span>
JavaScript
$('#input').on('keyup', function(){
var val = $(this).val().replace(/[ ](?!\s)/g, '-');
$('#output').text(val);
});
<input type="text" id="input">
<span id="output"></span>
$('#input').on('keyup', function(){
var val = $(this).val().replace(/[ ](?!\s)/g, '-');
$('#output').text(val);
});