FCC基础JS算法学习笔记

Reverse a String

function reverseString(str) {
a = str.split('');
b = a.reverse();
c = b.join('');
return c;
}

Factorialize a Number

function factorialize(num) {
var arr =[];
for (i=1;i<=num;i++){
arr.push(i);
}  
return arr.reduce(function(a,b){
return a * b;
 }, 1);
}

Check for Palindromes

function palindrome(str) {
ini = str.toLowerCase();
desym = ini.replace(/[\W_]/g,'');
a = desym.split('');
b = a.reverse();
c = b.join('');
if (c == desym){
return true;
  }else{    
  return false; 
 }
}

Find the Longest Word in a String

function findLongestWord(str) {
var max = 0;
a = str.split(' ');
for (i=0;imax){
max = a[i].length;
    }     
  }  
  return max;
}

Title Case a Sentence

function titleCase(str) {
a = str.toLowerCase().split(' ');
var result=a.map(function(val){
return val.replace(val.charAt(0), val.charAt(0).toUpperCase());
  });
  return result.join(' ');
}

Return Largest Numbers in Arrays

function largestOfFour(arr) {
  var res = [];
  for (i=0;i max){
        max = arr[i][j];
      }     
    }
    res.push(max);   
  }
 return res;

Confirm the Ending

function confirmEnding(str, target) {
  if (str.substr(-1)==target|str.substr(str.length-target.length)==target){
    return true;
  }else{
    return false;
  }
}

Repeat a string repeat a string

function repeatStringNumTimes(str, num) {
  if (num>=0){
  return str.repeat(num);  
  }else{
    return '';
  }
}