试试这个：

var input = 'lorem ipsum dolor sit amet';
// \w+ mean at least of one character that build word so it match every
// word and function will be executed for every match
var output = input.replace(/\w+/g, function(txt) {
  // uppercase first letter and add rest unchanged
  return txt.charAt(0).toUpperCase() + txt.substr(1);
}).replace(/\s/g, '');// remove any spaces

document.getElementById('output').innerHTML = output;

<div id="output"></div>

你也可以使用一个regex和一个replace：

var input = 'lorem ipsum dolor sit amet';
// (\w+)(?:\s+|$) mean at least of one character that build word
// followed by any number of spaces `\s+` or end of the string `$`
// capture the word as group and spaces will not create group `?:`
var output = input.replace(/(\w+)(?:\s+|$)/g, function(_, word) {
  // uppercase first letter and add rest unchanged
  return word.charAt(0).toUpperCase() + word.substr(1);
});

document.getElementById('output').innerHTML = output;

<div id="output"></div>

你可以使用一个简单的helper函数，比如：

return function (str) {
    return str.replace(/\w\S*/g, function(txt) {
        return txt.charAt(0).toUpperCase() + txt.substr(1);
    }).replace(/\s/g, "");
}

作为替代方案，您可以在空格上拆分字符串，将每个单词大写，然后将它们重新连接在一起：

"pascal case".split(' ').map(word => word.charAt(0).toUpperCase() + word.substring(1) ).join('')

Page有一个很好的例子，说明如何在JavaScript中将字符串中的每个单词大写：http://alvinalexander.com/javascript/how-to-capitalize-each-word-javascript-string

function wordSearch()
{
   var paragraph=document.getElementById("words").value;
   let para2=paragraph.replace(/\s+/g,'');//remove whitespaces
   let para3=para2.charAt(0).toUpperCase()+para2.slice(1); 
   //uppercase first letter
   alert(para3);
 }