JavaScript Math Object 数字
Math Object
The Math object allows you to perform mathematical tasks.
Math is not a constructor. All properties/methods of Math can be called by using Math as an object, without creating it.
Syntax
var x = Math.PI; // Returns PI
var y = Math.sqrt(16); // Returns the square root of 16
For a tutorial about the Math object, read our JavaScript Math Object tutorial.
Math Object Properties
| Property | Description |
|---|---|
| E | Returns Euler's number (approx. 2.718) |
| LN2 | Returns the natural logarithm of 2 (approx. 0.693) |
| LN10 | Returns the natural logarithm of 10 (approx. 2.302) |
| LOG2E | Returns the base-2 logarithm of E (approx. 1.442) |
| LOG10E | Returns the base-10 logarithm of E (approx. 0.434) |
| PI | Returns PI (approx. 3.14) |
| SQRT1_2 | Returns the square root of 1/2 (approx. 0.707) |
| SQRT2 | Returns the square root of 2 (approx. 1.414) |
Math Object Methods
| Method | Description |
|---|---|
| abs(x) | Returns the absolute value of x |
| acos(x) | Returns the arccosine of x, in radians |
| asin(x) | Returns the arcsine of x, in radians |
| atan(x) | Returns the arctangent of x as a numeric value between -PI/2 and PI/2 radians |
| atan2(y,x) | Returns the arctangent of the quotient of its arguments |
| ceil(x) | Returns x, rounded upwards to the nearest integer |
| cos(x) | Returns the cosine of x (x is in radians) |
| exp(x) | Returns the value of Ex |
| floor(x) | Returns x, rounded downwards to the nearest integer |
| log(x) | Returns the natural logarithm (base E) of x |
| max(x,y,z,...,n) | Returns the number with the highest value |
| min(x,y,z,...,n) | Returns the number with the lowest value |
| pow(x,y) | Returns the value of x to the power of y |
| random() | Returns a random number between 0 and 1 |
| round(x) | Rounds x to the nearest integer |
| sin(x) | Returns the sine of x (x is in radians) |
| sqrt(x) | Returns the square root of x |
| tan(x) | Returns the tangent of an angle |
实例:
<html>
<script type="text/javascript">
alert(Math.round(2.3));//四舍五入,2
alert(Math.random()*10);//１-９,5.369114940257843
alert(Math.min(5,10));//判断数字哪个较小,5
alert(Math.max(10,6));//数字哪个较大,10
</script>
</html>