JavaScript Trunc with Math.trunc() Method

The JavaScript trunc method will remove the decimals of a number and return just the integer, using the Math.trunc() method.

var num = Math.trunc(9.31);

The above code would return the number 9.

Some other examples of Math.trunc() are below:

var num = Math.trunc(1.123);
var num1 = Math.trunc(.6789);
var num2 = Math.trunc(1020.12);
var num3 = Math.trunc(-.54);
var num4 = Math.trunc(-50.98283);

Which would result in the following:

1
0
1020
0
-50

Math.trunc() in action using jQuery

Below we will provide code to let the user input a number, and then use the Math.trunc() method on that number. Here is our simple HTML setup:

<p>Type a number you want to use the Math.trunc() method on below:</p>
<input id="userVal" type="text" value="">
<input id="submitNum" type="submit" value="Submit">
<div id="results"></div>

Below is the JavaScript and jQuery code which take the user input using the jQuery click() or on() keypress methods, and use the Math.trunc() method on that user input and update the results below using the jQuery text() method.

$('#userVal').on('keypress',function(e) {
  if(e.which == 13) {
    $("#results").text(Math.trunc($("#userVal").val()));
  }
});
$("#submitNum").click(function(){
  $("#results").text(Math.trunc($("#userVal").val()));
});

The final code and output for this example is below:

Code Output:

Full Code:

<p>Type a number you want to use the Math.trunc() method on below:</p>
<input id="userVal" type="text" value="">
<input id="submitNum" type="submit" value="Submit">
<div id="results"></div>

<script>

$('#userVal').on('keypress',function(e) {
  if(e.which == 13) {
    $("#results").text(Math.trunc($("#userVal").val()));
  }
});
$("#submitNum").click(function(){
  $("#results").text(Math.trunc($("#userVal").val()));
});

</script>

Hopefully this article has been useful in helping you understand how the JavaScript Math.trunc() method works.