// 字符串首字母转大写，后面字母小写
/**
 * 方法一：js字符串切割
 * @param {*} str 
 */
function firstToUpper1(str) {
    return str.trim().toLowerCase().replace(str[0], str[0].toUpperCase());
}
/**
 * 方法二：js正则
 * @param {*} str 
 */
function firstToUpper2(str){
    return str.replace(/\b(\w)(\w*)/g, function($0, $1, $2) {
        return $1.toUpperCase() + $2.toLowerCase();
    });
}
/**
 * 方法三：js正则
 * @param {*} str 
 */
function firstToUpper3(str){
    return str.toLowerCase().replace(/( |^)[a-z]/g,(L)=>L.toUpperCase());
}
/**
 * 方法三：css
 */
// text-transform: capitalize;

let str='hELLO'
console.log(firstToUpper1(str));
console.log(firstToUpper2(str));
console.log(firstToUpper3(str));

// 字符串反转
/**
 * 方法一：js字符串反转 
 * unshift()
 */
var name = "My city is WH";
var nameArr = name.split('');
var result=[];
var resultStr = '';
for (var i = 0, l = nameArr.length; i < l; i++) {
    result.unshift(nameArr[i]);

}
for (var i = 0, l = result.length; i < l; i++) {
    resultStr += result[i];
}
console.log(resultStr);  // HW si ytic yM


/**
 * 方法二：js字符串反转 
 * reverse()，join()
 */

var name = "My city is WH";
var resultStr = name.split('').reverse().join(''); 
console.log(resultStr);  // HW si ytic yM

 

/**
 * 方法三：js字符串反转 
 * charAt()
 */


var name = "My city is WuHan";
var nameArr = name.split('');
var resultStr = '';
for (var i = nameArr.length-1; i >= 0; i--) {
    resultStr += name.charAt(i);
}
console.log(resultStr); // naHuW si ytic yM