I want to use function with while to print only 10 numbers starting from the number I choose.
But while loop doesn't stop looping.
id = prompt('Write any number.');
function numbering(a) {
var i = a;
var j = a + 10;
while (i < j) {
document.write(i);
i++;
}
};
numbering(id);Try this:
var id = parseInt(prompt('Write any number.'), 10);
In your example id will be of type string and the comparisons won't work as you expect.
When you use function numbering(a) {, the variable a is passed as string.
This results in i and j being set as string.
Taking example:
Suppose you pass 2 as input, your variables will be set as a="2", i="2" and j="210". So according to your condition, it'll print starting from 2 till 209.
You can change your code to parse a as number to achieve your result; something like:
function numbering(a) {
a = parseInt(a); //parse as Int here
var i=a; var j=a+10;
while (i < j)
{
document.write(i);
i++;
}
};
Try it with a for-loop:
for(var i=0; i<10; i++){ doSomething}
You can try with this for-loop function :
id=prompt('Write any number.');
function numbering(a) {
for (let i = a; i < a + 10; i++){
document.write(i);
}
};
numbering(id);You can add a parseInt(id) to you numbering function parameter call if you want to parse the input into a number
When you enter a number in the prompt, it is supplied as a string. Since you have not converted this into a number, the line var j = a + 10 is actually joining the two values as if they were strings.
For example, if you enter "5" into the prompt, then var j = "5" + 10 returns "510". Only when you then compare the two variables in the while loop with i < j does it get interpreted as a number, and will loop from 5 to 510.
The easiest way to convert a string into a number is to use parseInt(value).
The prompt function returns a string.
The problem is that you are concatenating a string with the number 10.
If you write your variables to document, you can see the problem:
id=prompt('Write any number.');
function numbering(a) {
var i=a; var j=a+10;
document.write(i);
document.write("<br/>");
document.write(j);
document.write("<br/>");
//while (i < j){
// document.write(i);
// i++;
//}
};
numbering(id);
This will fix your problem:
var id=parseInt(prompt('Write any number.'));
you need the parseInt function because what you getting from promt is string. For example 5 +10 . For javascript , it will be 510 .
id=prompt('Write any number.');
function numbering(a) {
var i=parseInt(a); var j=parseInt(a)+10;
while (i < j){
document.write(i);i++;
}};
numbering(id);
document.write(i +"<br>");
In console i am getting proper result. just add line break to see whole result in viewport
document.writewithinsertAdjacentHTML().a = +a;. The unary operator (+) will cast the variableato a number, since prompts actually returnsstrings, so using + on strings will result in concatenating.