When I Input the first number to be for example 5 and the second Number to be like 10 I get undefined. I tried alert(array); to see the contents of it but there was nothing and hence undefined. It works for other numbers like 1 to 9. Why does it give me an undefined value from range 5 to 10? I just want to make a random number chooser where you will input the first number and the second number and a random number will be given to you?
function promptUser() {
var first = prompt("First number?");
var second = prompt("Second number?");
var array = [];
//Make a range from First number to last number then choose a random number
for (x = first; x <= second; x++) {
array.push(x);
}
alert(array);
randomInt = Math.floor(Math.random() * array.length);
alert("The random number is " + array[randomInt]);
}
Satpal
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3 Answers 3
prompt() returns the result in string literal, you need to use parseInt() or other methods to convert string to Number.
var first = parseInt(prompt("First number?"), 10);
var second = parseInt(prompt("Second number?"), 10);
var array = [];
for (x = first; x <= second; x++) {
array.push(x);
}
randomInt = Math.floor(Math.random() * array.length);
console.log(array, randomInt, "The random number is " + array[randomInt]);Additionally, alert() is not a debugging tool, Learn to use Console
answered Jan 16, 2017 at 8:56
Satpal
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Comments
your first number is being treated as string needed to be parsed as int
function promptUser(){
var first = prompt("First number?");
var second = prompt("Second number?");
var array = [];
<!--Make a range from First number to last number then choose a random number-->
for (x = parseInt(first); x <= parseInt(second); x++){
array.push(x);
}
console.log(array);
randomInt = Math.floor(Math.random()*array.length);
console.log(randomInt);
alert("The random number is " + array[randomInt]);
}
promptUser();
answered Jan 16, 2017 at 9:00
Mitesh Pant
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Comments
Use:
var first = parseInt(prompt("First number?"));
var second = parseInt(prompt("Second number?"));
instead of:
var first = prompt("First number?");
var second = prompt("Second number?");
prompt returns string
Comments
lang-js