/********************* var arr = [4,3,2,5]; for(var i=1;i<=2;i++){ arr[i]=arr[i+1] + arr[i+1]; } document.write(arr+"\n"); // = 4,4,10,5 *********************/ /********************* Explaination: Elements 1 and 4 remain unchanged. First Cycle: arr[i]=arr[i+1] + arr[i+1] arr[1]=arr[2] + arr[2] arr[1]=2+2 arr[1]=4 Second Cycle: arr[i]=arr[i+1] + arr[i+1] arr[2]=arr[3] + arr[3] arr[2]=5+5 arr[2]=10 *********************/ /********************* var arr = [4,3,2,5]; for(var i=1;i<=2;i++){ arr[i]=arr[i-1] + arr[i+1]; } document.write(arr+"\n"); // = 4,6,11,5 *********************/ /********************* Explaination: The value of the array begins with the start value of i=1, therefore arr[0]=4 remains unchanged. This also holds true with the fourth array element. This loop only runs twice, starts at 1 and ends at 2. First iteration: arr[i]=arr[i-1] + arr[i+1] arr[1]=arr[0] + arr[2] arr[1]=4+2 arr[1]=6 Second iteration: arr[2]=arr[i-1] + arr[i+1] arr[2]=arr[1] + arr[3] arr[2]=6+5 // **Remember** arr[1] changed to 6 after first iteration arr[2]=11 *********************/ /******************** var arr = [4,3,8]; for(var i=0;i<2;i++){ arr[i]+=arr[i+1]; document.write(arr[i]+"\n"); } document.write(arr+"\n"); // = 7, 11, 8 ********************/ /******************** Explaination: First iteration: i=0 arr[0]+arr[1]=7 4+3=7 Second iteration: i=1 arr[1]+arr[2]=11 3+8=11 Third iteration: i=2 2<2=False The 3rd element "8" remains the same ********************/ /******************** var b = [7,9,3,4]; for(var i=1;i<4;i++){ b[0]+=b[i]+1; document.write(b[i] + "\n"); // = Value after each run 17, 21, 26 } document.write(b[0]+"\n"); // = 26 ********************/ /******************** Explaination: 7+9+1=17 17+3+1=21 21+4+1=26 ********************/ /******************** var arr = [1,2,3,4]; var x = 1; for(var j=0;j0){ res=sum%2+res; sum=Math.floor(sum/2); } return res; } document.write(addBinary(2,5)); **************/ /************** Explaination: First iteration: sum=a+b sum=2+5 7>0 is True res=sum%2+res res=7%2+0 res="1" sum=Math.floor(sum/2) sum=Math.floor(7/2) sum=Math.floor(3.5) sum=3 Second iteration: 3>0 is True res=sum%2+res res=3%2+"1" // The data type of "res" is a string so the "1" gets concatenated, not added. res="11" // This is why "res" now equals "11" instead of eleven. sum=Math.floor(sum/2) sum=Math.floor(3/2) sum=Math.floor(1.5) sum=1 Third iteration: 1>0 is True res=sum%2+res res=1%2+"1" res="111" // Concatenated string. sum=Math.floor(sum/2) sum=Math.floor(1/2) sum=Math.floor(.5) sum=0 Fourth iteration: 0>0 is Flase, Loop ends. // Note that there is a shortcut to solving these problems if you understand binary bit position values. **************/ /************** var a=50; function myfunc(){ let a=5; return a; } myfunc(); document.write(a+"\n"); // = 50 var a=50; function myfunc(){ var a=5; return a; } myfunc(); document.write(a+"\n"); // = 50 var a=50; function myfunc(){ let a=5; return a; } document.write(myfunc()+"\n"); // = 5 **************/

Test Prep