js将字符串中的每一个单词的首字母变为大写其余均为小写

• 方法一

var str = "You seE whaT you believe!"

function changeStr(str) {
    var arr = str.toLowerCase().split(" ");
    arr.forEach((item, index, array) => {
        arr[index] = item[0].toUpperCase() + item.substring(1, item.length);
    });
    return arr.join(" ");
}

console.log(changeStr(str)); //You See What You Believe!ascript

• 方法二

var str = "You seE whaT you believe!"

function changeStr(str) {
    var arr = str.toLowerCase().split(" ");
    arr.forEach((item, index, array) => {
        arr[index] = Array.prototype.map.call(item, function(v, i) {
            return i == 0 ? v.toUpperCase() : v;          
        }).join("");
    });
    return arr.join(" ");
}

console.log(changeStr(str)); //You See What You Believe!