1、通过Math.max()和Math.min()和Array.reduce()来实现数组中从小到大的累积和 ，例如sumAll([1,5]) 值为10
function sumAll(arr) {
var arryA=[];
var max=Math.max.apply(null,arr);
var min=Math.min.apply(null,arr);
var sum=0;
var sumFun=function(max,min){
for(var i=0;i<(max-min+1);i++){
arryA.push(min+i);
}
console.log(arryA);
var value=arryA.reduce(function(previousValue,currentValue){
return previousValue+currentValue;
});
return value;
};
sum=sumFun(max,min);
return sum;
}
console.log(sumAll([5, 10]));
关键点，通过Math.max.apply(null,array)来实现数组中的最大值判断
2、数组去重然后合并不同的数组
使用Array.indexOf() Array.slice() Array.filter() Array.concat()
function diffArray(arr1, arr2) {
var newArr = [];
var arrA=[];
var arrB=[];
var arrMiddle=[];
if(arr1.length===0||arr2.length===0){//判断是否存在[]的情况
console.log(arr2.concat(arr1))
}else{
arrA=arr1.filter(function(ele,index){
var flag=true;
var element=null;
for(var i=0;i<arr2.length;i++){
if(ele===arr2[i]){
flag=false;
element=ele;
}
}
if(element!=null){
arrMiddle.push(element);
}
return flag;
});
if(arrMiddle.length>0){//是否存在各不相同的情况
var num;
for(var k=0;k<arrMiddle.length;k++){
num=arr2.indexOf(arrMiddle[k]);
arr2.splice(num,1);
}
console.log(arr2);
arrB=arr2;
}else{
arrB=arr2;
}
newArr=arrA.concat(arrB);
}
// Same, same; but different.
return newArr;
}
console.log(diffArray([1, "calf", 3, "piglet"], [7, "filly"]))
3、分析一个数组包含的多个json格式对象，是否含有另一个json格式的对象的内容。
Where art thou
function whereAreYou(collection, source) {
// What's in a name?
var arr = [];
// Only change code below this line
var value=Object.keys(source);
for(var i=0;i<collection.length;i++){
if(Object.keys(collection[i]).length>=Object.keys(source).length){
var flag=true;
for(var key in source){
if(collection[i].hasOwnProperty(key) ){
if(collection[i][key]!=source[key]){
flag=false;
}
}else{
flag=false;
}
}
if(flag){
arr.push(collection[i]);
}
}
}
// Only change code above this line
return arr;
}
console.log(whereAreYou([{ "a": 1, "b": 2 }, { "a": 1 }, { "a": 1, "b": 2, "c": 2 }], { "a": 1, "b": 2 }))
whereAreYou([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], { last: "Capulet" })should return [{ first: "Tybalt", last: "Capulet" }].
whereAreYou([{ "a": 1 }, { "a": 1 }, { "a": 1, "b": 2 }], { "a": 1 }) should return [{ "a": 1 }, { "a": 1 }, { "a": 1, "b": 2 }].
whereAreYou([{ "a": 1, "b": 2 }, { "a": 1 }, { "a": 1, "b": 2, "c": 2 }], { "a": 1, "b": 2 }) should return [{ "a": 1, "b": 2 }, { "a": 1, "b": 2, "c": 2 }].
whereAreYou([{ "a": 1, "b": 2 }, { "a": 1 }, { "a": 1, "b": 2, "c": 2 }], { "a": 1, "c": 2 }) should return [{ "a": 1, "b": 2, "c": 2 }].
4、搜索指定字符串，替换成指定字符串
Search and Replace
function myReplace(str, before, after) {
var afterWord;
if((before.charCodeAt(0)>=65)&&(before.charCodeAt(0)<=90)){
console.log(1);
afterWord=after.replace(after.charAt(0),after.charAt(0).toUpperCase());
}else{
afterWord=after;
}
return str.replace(before,afterWord);
}
console.log(myReplace("Let us go to the store", "store", "mall"))
注意首字母大写
5、拉丁猪算法，如果一个字符串包含元音字母aeiou，就把元音字母以前的字符串剪切到末尾，并且加上ay，如果首字母就是元音字母，就在末尾加上way
Pig Latin
function translatePigLatin(str) {
var yuanArr=["a","e","i","o","u","A","E","I","O","U"];
var index=0;
var result="";
var word1="";
var word2="";
for(var i=0;i<str.length;i++){
if(yuanArr.indexOf(str[i])>-1){
index=i;
break;
}
}
if(index>0){
word1=str.substr(0,index);
word2=str.substr(index,str.length-index);
result=word2+word1+"ay";
}else if(index===0){
result=str+"way";
}
return result;
}
console.log(translatePigLatin("algorithm"))
console.log(translatePigLatin("california"))
6、DNA配对，根据A-T C-G这样配对
DNA Pairing
function pairElement(str) {
var arryA=["A","T","C","G"];
var arryB=["T","A","G","C"];
var word=str.split("");
var index=0;
var arrAll=[];
for(var i=0;i<word.length;i++){
for(var j=0;j<arryA.length;j++){
if(word[i]===arryA[j]){
index=j;
}
}
var arrOne=[];
arrOne[0]=word[i];
arrOne[1]=arryB[index];
arrAll.push(arrOne);
}
return arrAll;
}
console.log(pairElement("GCG"))
pairElement("ATCGA") should return[["A","T"],["T","A"],["C","G"],["G","C"],["A","T"]]
pairElement("TTGAG") should return[["T","A"],["T","A"],["G","C"],["A","T"],["G","C"]].
7、识别一个字符串按照字母顺序少了哪一个字母
function fearNotLetter(str) {
var arryA=[];
var word=str;
var index=0;
var letter;
var flag=0;
for(var i=0;i<word.length;i++){
arryA.push(word.charCodeAt(i));
}
flag=arryA[0];
for(var j=0;j<arryA.length;j++){
if(arryA[j]!=flag){
index=arryA[j]-1;//取得不相同字母的上一位，-1取得失去的那一个
break;//只要有一个不同，马上停止
}
flag++;
}
if(index!=0){
letter=String.fromCharCode(index);
}else{
letter=undefined;
}
return letter;
}
console.log(fearNotLetter("abcdefghjklmno"));
fearNotLetter("abce") should return "d".
fearNotLetter("bcd") should return undefined.
8、判断参数是否是布尔类型
Boo who
function booWho(bool) {
// What is the new fad diet for ghost developers? The Boolean.
var word=bool;
if(word===true && word===false){
return true;
}else{
return false;
}
}
console.log(booWho(null));
9、多个数组（包括二维数组）进行合并去重
Sorted Union
function uniteUnique(arr1, arr2, arr3) {
var newArray=[];
var allArray=Array.prototype.concat.apply([], arguments)
for(var i=0;i<allArray.length;i++){
if(newArray.indexOf(allArray[i])===-1){
newArray.push(allArray[i]);
}
}
return newArray;
}
console.log(uniteUnique([1, 3, 2], [1, [5]], [2, [4]]));
重点：由于有多个数组参数，需要用Array.prototype.concat.apply([],arugument)进行合并，用apply的原因是支持第二个参数为数组形式的
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