Detailed explanation of loop usage in javascript examples

I was bored and sorted out some simple exercises about loops. I hope it will be helpful to those who are just starting to learn JS.

1. Print the number and sum of all multiples of 7 between 1 and 100

var sum=0;
var n=0;
for(var i=1;i<=100;i++){
	if(i%7==0){
		sum+=i;
		++n;
		}
	}
console.log("The number is: "+n+", the sum is: "+sum);

Running results:

2. Assuming the annual interest rate of investment is 5%, how many years will it take to increase from 1,000 to 5,000?

var money=1000;
var i=0;
while(money<=5000){
	money=money*1.05;
	++i;
}
console.log("A total of "+i+" years is required");

Running results:

3. Find the daffodil number between 100 and 1000. A daffodil number is a 3-digit number where the sum of the 3 powers of each digit is equal to itself. For example, 1^3 + 5^3 + 3^3 = 153

for(var i=100;i<1000;i++){
	//Get the number in the hundreds place var a=parseInt(i/100);
	//Get the number in the tens place var b=parseInt(i/10%10);
	// Extract the number in the ones place var c=parseInt(i%10);
	 if(a*a*a+b*b*b+c*c*c==i){
	    console.log(i);
		}
}

The tens digit can also be obtained using var b=paraseInt((i-bai*100)/10).

Running results:

4. Print the sum of all odd numbers between 1-100. All numbers that are not divisible by 2 are odd numbers.

var sum=0;
for(var i=1;i<=100;i++){
	if(i%2==0){
		sum+=i;
	}
}
console.log("The sum of odd numbers is: "+sum);

Running results:

5. Determine the prime numbers between 2-100. A prime number is a natural number greater than 1 that cannot be divided by any other natural numbers except 1 and itself.

for(var i=2;i<=100;i++){
	var flag = true;
	//If the loop reaches i, there will be repeated factors for(var j=2;j<=Math.sqrt(i);j++){
		if(i%j==0){
			flag=false;
			break;
		}
	}
	if(flag==true){
		document.write(i+"&nbsp");
	}
}

Running results:

6. Printing triangle

From little to more

for(var i=1;i<=5;i++){
	for(var j=1;j<=i;j++){
		document.write("*");
	}
	document.write("<br/>");
} 

From more to less

for(var i=0;i<5;i++){
	for(var j=0;j<5-i;j++){
		document.write("*");
	}
	document.write("<br/>");
} 

7. Print the multiplication table

for(var i=1;i<=9;i++){
	for(var j=1;j<=i;j++){
		document.write(i+"*"+j+"="+i*j+"&nbsp;&nbsp;")
	}
	document.write("<br/>");//line break}

Running results:

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