JavaScript初级算法学习笔记(1)

字符串中每个单词首字母大写

一、正常思路 使用for循环

function titleCase(str){
    var a = str.toLowerCase().split(' ');
    var len = a.length;
    var b = [];
    for(i=0;i<len;i++){
        a[i] = a[i][0].toUpperCase() + a[i].slice(1);
    }
    b = a.join(' ');
    return b;
}
var title = titleCase("I'm a little tea pot");
console.log(title);//I'm A Little Tea Pot

二、map+数组

function titleCase(str){
    var a = str.toLowerCase().split(' ');
    var b = a.map(function(item){
        return item[0].toUpperCase() + item.slice(1);
    });
    return b.join(' ');
}
var title = titleCase("I'm a little tea pot");
console.log(title);//I'm A Little Tea Pot

三、数组+reduce

function titleCase(str){
    var a = str.toLowerCase().split(' ');
    var b = a.reduce(function(prev,cur){
        return prev[0].toUpperCase()+prev.slice(1) + ' '+cur[0].toUpperCase() + cur.slice(1);
    });
    return b;
}
var title = titleCase("I'm a little tea pot");
console.log(title);//I'm A Little Tea Pot

四、正则表达式+replace

function titleCase(str){
    var a = str.toLowerCase().replace(/\b([\w|']+)\b/g,function(s){
   return s.slice(0,1).toUpperCase()+s.slice(1);
  });
    return a;
}
var title = titleCase("I'm a little tea pot");
console.log(title);//I'm A Little Tea Pot

五、正则表达式（es6语法）

function titleCase(str){
    return str.toLowerCase().replace(/( |^)[a-z]/g, (L) => L.toUpperCase());
}
var title = titleCase("I'm a little tea pot");
console.log(title);//I'm A Little Tea Pot

注：纯属个人学习笔记。