So basically I have a for loop and I am trying to get it to run x amount of times. Depending on what the user inputs. The issue I am having is how to get the user input and also make sure that its a number not any other type of input. making them try again if its wrong.
6 Answers
It's simple really
Input Number : <input id="numberinput" onkeypress="return event.charCode >= 48 && event.charCode <= 57" />
<button id="btn" onclick="doAction()">
Send
</button>
<script>
var doAction = function () {
var input = document.getElementById('numberinput');
var times = parseint(input.value);
for(var i = 0; i < times; i++) {
//do whatever you need to do
}
}
</script>
Comments
In HTML5 you can use <input type="number"> to restrict an input to numeric characters only.
For older browsers, that are not HTML5-compatible, use <input type="text" onkeypress='return event.charCode >= 48 && event.charCode <= 57'></input>. This utilizes Javascript to make sure that only numeric input is accepted into the input box.
Check out the snippet below for both solutions in action:
Javascript-based:<input type="text" onkeypress='return event.charCode >= 48 && event.charCode <= 57'></input>
<br><br>
HTML5 solution (preferred):<input type="number">
Comments
HTML
<input type="number" id="myInput">
<button id="myButton">Run Loop</button>
Javascript
$('body').on('click', '#myButton', function() {
var input = $('#myInput').val();
for(var i = 0; i < input; i++) {
alert('You have written inside input field: ' + input + ". This is Alert #" + (i+1))
}
});
Comments
To get the value from the input, you can use the value property of the input element.
To make sure the input is a number, you can specify type="number" if HTML5 is supported as mentioned in Angelos Chalaris's answer.
document.getElementById('btn').onclick = function(){
var totalIterations = parseInt(document.getElementById('input').value);
var output = document.getElementById('output');
output.innerHTML = '';
for(var i = 1; i <= totalIterations; i ++) {
var item = document.createElement('div');
item.innerHTML = i;
output.appendChild(item);
}
};<input id="input" type="number"/>
<input id="btn" type="button" value="Do loop"/>
<div id="output"></div>
Comments
Here is an example using user input dialog:
var input, parsedInput = 0;
do {
input = prompt("Please enter valid number", "1");
parsedInput = parseInt(input);
} while(isNaN(parsedInput) || parsedInput < 0);
// keep trying on invalid input or negative number
for( i=0; i< parsedInput ; i++){
console.log("loop " + i);
}
Comments
HTML:
<input type="text" name="somefield" id="someid" value="10" />
JS:
var userInput = document.getElementById('someid').value;
if( Number.isInteger(parseInt(userInput)) )
{
// do something
}
Also, Number.isInteger() does not work on Internet explorer 11 or earlier.
1 Comment
AmN
Thank you @angelos-chalaris
<input type="number">i guess?