JavaScript符串中每个单词的首字母大写化

map() + replace()

function titleCase(str) {
    var convertToArray = str.toLowerCase().split(" ");
    var result = convertToArray.map(function(val){
        return val.replace(val.charAt(0), val.charAt(0).toUpperCase());
    });
    return result.join(" ");
}
titleCase("hello world");   //"Hello World"

for ··· in + replace()

function titleCase(str) {
    str = str.toLowerCase().split(‘ ‘);
    for (var i in str) {
        str[i] = str[i].replace(str[i].charAt(0), str[i].charAt(0).toUpperCase());
    };
    return str.join(‘ ‘);
}
titleCase("hello world");   //"Hello World" 

map() + slice()

function titleCase(str) {
    return str.toLowerCase().split(‘ ‘).map(function(word) {
        return (word.charAt(0).toUpperCase() + word.slice(1));
    }).join(‘ ‘);
}
titleCase("hello world");  //"Hello World"