How to make a triangle using for loop javascript
I'm sure there are better solutions (simply left-padding with spaces comes to mind), but here's the quick and dirty one I created from your own solution.
for (var i = 0; i < 5; i++) {
for (var j = 0; j < i; j++) {
document.write(" ");
}
for (var j = 5; j > i; j--) {
document.write("#");
if (j > i + 1) document.write(" ");
}
document.write('<br/>')
}
https://js.do/code/diamondsinthesky
how do i make a triangle using for loop in javascript which output matches the parameter content
let printTriangle = (num) => {
let result = "";
for ( let i = 0; i < num; i++) {
for (let j = 0; j <= i; j++) {
result += '*';
}
result += "\n";
}
return result;
}
console.log(printTriangle(5));
how to make isosceles triangle in javascript?
The below code will give you the desired output.
function pyramid(N){
let result = "";
for(let i = 1 ; i <= N ; i++) {
for(j = N ; j > i ; j--) {
result += " ";
}
for(j = 1 ; j<= i ; j++) {
result += i + " ";
}
result += "\n";
}
return result;
}
console.log(pyramid(5));
looping a triangle with a while loop
It's the result of the final expression in your code. Type in "5+5" in your JS console and you'll get a result. If you put "5+5" at the end of a script, same thing. That's what's happening here:
var result = "#"
while(result.length <=7 ){
console.log(result);
result = result + "#"; // <-- this is the last statement executed, so it is returned
}
In contrast, the last statement below is a logging statement, which has no return value. So the result of the script is undefined
.
for (var result = "#"; result.length <=7; result = result + "#")
console.log(result);
You can see this more clearly if you try something like this:
for (var i=0; i < 5; i++) {
console.log(i);
i
}
Here, the last expression is simply i
. This code prints each number from 0-4 inclusive, then prints the 4 a second time because its the final expression.
0
1
2
3
4 <-- the final console.log() call
4 <-- the final expression
how to make a row of triangles using loops?
You can use the iteration (i) and multiply it by the spacing you want and add it to the x value.
function showDrawing() {
let coolCanvas = document.getElementById("canvas");
let ctx = coolCanvas.getContext("2d");
ctx.lineWidth = 5;
for (let i = 0; i < 5; i += 1) {
ctx.beginPath();
ctx.moveTo(126+(i*170), 300);
ctx.lineTo(200+(i*170), 400);
ctx.lineTo(50+(i*170), 400);
ctx.closePath();
ctx.strokeStyle = 'blue';
ctx.fillStyle = 'purple';
ctx.fill();
ctx.stroke();
}
}
<canvas id="canvas" width="1500" height="700" style="border:3px solid #000000;">
</canvas>
<button onclick="showDrawing()">Drawing</button>
Upside down triangle using one for-loop
Your code is fine, Just get rid of triangleStr
and replace it inside for-loop
with method repeat
.
function triangle(num) {
for (let i = num; i > 0; i--)
{
console.log("#".repeat(i));
}
}
triangle(5);
Result
#####
####
###
##
#
How to use a For Loop to make a triangle out output of the inputted numbers in JavaScript
Look at the documentation for window.prompt()
.
Remove .value
. input
is the value.
Also, you aren't telling your code to not run if input
is "bad".
// Be in a function so that you can return(function() {
var input = prompt("Enter a number: ");
if (!input) { alert("Either you entered a NaN or you left an empty field. \nPlease enter some number!"); // Get of of the function return; }
for (input = 10; input <= 15; input++) { var a = ''; for (var j = 10; j <= input; j++) { var a = a + '' + input; }
document.writeln(a + "<BR>");
}}());
Shorter Way of Prinitng Triangle Patterns JavaScript
If you want to use only one loop, you can use repeat()
method in ECMAScript6 or higher.
For Right triangle:
const line = 5;
let rightTriangle = "";
for (let l = 1; l <= line ; l++) {
const indent = line-l;
rightTriangle += `${" ".repeat(indent)}${"*".repeat(l)}${"\n"}`;
}
console.log(rightTriangle);
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