Math atan2() Method - Javascript Math

Javascript examples for Math:atan2

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Description

The atan2() method returns the arctangent of the quotient of its arguments, as a numeric value between PI and -PI radians.

Parameter Description
y Required. A number representing the y coordinate
x Required. A number representing the x coordinate

Return Value:

A Number, from PI to -PI, or NaN if the value(s) are empty

you had a point with the (x,y) coordinates of (4,8), you could calculate the angle in radians between that point and the positive X axis as follows:

Demo Code

ResultView the demo in separate window 

<!DOCTYPE html>
<html>
<body>

<button onclick="myFunction()">Test</button>

<p id="demo"></p>

<script>
function myFunction() {//w  w  w .  j a v  a2 s.c o m
    document.getElementById("demo").innerHTML = Math.atan2(8, 4);
}
</script>

</body>
</html>

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