2.1 Looping a triangle (Eloquent JavaScript Solutions)

2-1 Eloquent Javascript Solutions.js

for (var triangle = "#"; triangle.length <= 7; triangle += "#") 
  console.log(triangle);

Program Structure

2.1 Looping a triangle

Write a loop that makes seven calls to console.log to output the following triangle:

// #
// ##
// ###
// ####
// #####
// ######
// #######

It may be useful to know that you can find the length of a string by writing .length after it.

var abc = "abc";
console.log(abc.length);
// → 3

Most exercises contain a piece of code that you can modify to solve the exercise. Remember that you can click code blocks to edit them.

Hints

You can start with a program that prints out the numbers 1 to 7, which you can derive by making a few modifications to the even number printing example given earlier in the chapter, where the for loop was introduced.

Now consider the equivalence between numbers and strings of hash characters. You can go from 1 to 2 by adding 1 (+= 1). You can go from "#" to "##" by adding a character (+= "#"). Thus, your solution can closely follow the number-printing program.

var x='';
for(let i=0; i <8; i++){
x= '#'+ x;
console.log( x );
}

Just tried without using a for loop

Array(7).fill().map((_, i) => '#'.repeat(i + 1)).join('\n');
// "#
// ##
// ###
// ####
// #####
// ######
// #######"

counter="#";
for(let number=0;number<7;number++){
console.log(counter);
counter+="#";
}

In the spirit of “there’s no such thing as a stupid question”

Why does the one below work:

for ( var triangle = “#”; triangle.length <=7; triangle += “#”)
console.log(triangle);

When the next one doesn’t? I transferred the for loop into a while loop and expected the outcome to be the same. But instead of starting at 1 # it starts at 2.

let triangle = “#”;
while (triangle.length <=7) {
triangle += “#”;
console.log(triangle);
}

This is my first outing into JavaScript and I’m starting to think it isn’t for me.

Hey @worgraeme - this stuff can be tricky so keep going!
It's because you initialised triangle with a value of # so it already has one hash in it. Then you added another hash in the while loop before logging to the console where you see two #s
To fix this, initialise triangle with an empty string:
let triangle = "";

Thank you so much for your help. That is shockingly simple.

trying to create one that takes any value and creates a triangle

const loopTriangle = (loopCounter)=>{
let num=' ';
for (let i = 0;i<loopCounter;i++){
num +=" #";

console.log(num);
}
};
if you run the function it will create your desired triangle

//loopTriangle(10)