JavaScript面试库

var str = "web-kit-index";
function to(str){
    var j = str.split("-");
    for(var i=1,len=j.length;i<len;i++){
        j[i] = j[i].charAt(0).toUpperCase()+j[i].substring(1);
    }
    return j.join("");
}
console.log(to(str));

或

function to(str){
    var reg = /-(\w)/g;
    return str.replace(reg,function(a,b){
        return b.toUpperCase();
    })
    
}
console.log(to(str));

var str = "wwwwaaaa";
function max(str){
    var obj = {};
    for(var i=0,len=str.length;i<len;i++){
        if(!obj[str[i]]){
            obj[str[i]] = [];
            obj[str[i]].push(str[i]);
        }else{
            obj[str[i]].push(str[i]);
        }
    }
    var num = 0,value;
    for(var k in obj){
        if(obj[k].length>num){
            num = obj[k].length;
            value = k;
        }
    }
    return "出现最多的是："+obj[value][0]+" 出现了："+num+"次";
}
console.log(max(str));

或

function max(str){
    var s = str.split("").sort().join("");
    var reg = /(\w)\1+/g;
    var num = 0;
    var value = null;
    s.replace(reg,function($0,$1){
        if(num<$0.length){
            num = $0.length;
            value = $1;
        }
    })
    return "出现最多的是："+value+" 出现了："+num+"次";
}
console.log(max(str));

var str = "js123werw13weragadsg324ererrer5555";
var num = ‘‘;
var arr = [];
for(var i=0;i<str.length;i++){
    if(!isNaN(+str[i])){
        num += str[i];
        if(isNaN(+str[i+1])){
            arr.push(+num);
            num = "";
        }
    }
}
console.log(arr);

var str = "13224242311012101";
function san(){
    var first = (str.length)%3;
    var s = str.substring(0,first);
    var reg = str.substring(first);
    var arr = [];
    if(first!==0){
        arr.push(s);
    }
    var t = "";
    for(var i=0;i<reg.length;i++){
        t+=reg[i];
        if(i%3===2){
            arr.push(t);
            t = "";
        }
    }
    return arr.join(",");
    
}
console.log(san(str));

function san(str){
    var reg = /(?=(?!\b)(\d{3})+$)/g;
    return str.replace(reg,",");
}
console.log(san(str));

var a = 12;
var b = 20;

a = a + b;
b = a - b;
a = a - b;

console.log(a);
console.log(b);

或

var str1 = ‘love‘;
var str2 = ‘Js‘;
str1 = [str1,str2];
str2 = str1[0];
str1 = str1[1];

console.log(str1);
console.log(str2);

方法1：只支持数字

var num = 10;
function a(num){
    var arr = [];
    return (function(){
        arr.unshift(num);
        num--;
        if(num!=0){
            arguments.callee();
        }
        return arr;
    }());
}
console.log(a(num)); [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

function a(num){
    var arr = [];
    arr.length = num+1;
    arr = arr.join("a");
    var arr2 = [];
    arr.replace(/a/g,function(){
        arr2.unshift(num--);
    })
    return arr2;
}
console.log(a(num)); [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

var arr = [1, 2, 3, 4, 5, 6, 7, 8];
function sort(arr){
    for(var i=0;i<arr.length-1;i++){
        var cur = Math.floor(Math.random()*(i+1));
        var tel = arr[i];
        arr[i] = arr[cur];
        arr[cur] = tel;
    }
    return arr;
}
console.log(sort(arr));