Math.max()

Math.max() 函式會回傳零或多個數字中的最大值。

語法

Math.max([value1[, value2[, ...]]])

Parameters

value1, value2, ...
Numbers.

Return value

The largest of the given numbers. If at least one of the arguments cannot be converted to a number, NaN is returned.

說明

Because max() is a static method of Math, you always use it as Math.max(), rather than as a method of a Math object you created (Math is not a constructor).

If no arguments are given, the result is -Infinity.

If at least one of arguments cannot be converted to a number, the result is NaN.

範例

Using Math.max()

Math.max(10, 20);   //  20
Math.max(-10, -20); // -10
Math.max(-10, 20);  //  20

Getting the maximum element of an array

Array.reduce() can be used to find the maximum element in a numeric array, by comparing each value:

var arr = [1,2,3];
var max = arr.reduce(function(a, b) {
return Math.max(a, b);
});

The following function uses Function.prototype.apply() to get the maximum of an array. getMaxOfArray([1, 2, 3]) is equivalent to Math.max(1, 2, 3), but you can use getMaxOfArray() on programmatically constructed arrays. This should only be used for arrays with relatively few elements.

function getMaxOfArray(numArray) {
return Math.max.apply(null, numArray);
}

The new spread operator is a shorter way of writing the apply solution to get the maximum of an array:

var arr = [1, 2, 3];
var max = Math.max(...arr);

However, both spread (...) and apply will either fail or return the wrong result if the array has too many elements, because they try to pass the array elements as function parameters. See Using apply and built-in functions for more details. The reduce solution does not have this problem.

規範

Specification Status Comment
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.0.
ECMAScript 5.1 (ECMA-262)
The definition of 'Math.max' in that specification.
Standard
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.max' in that specification.
Standard
ECMAScript Latest Draft (ECMA-262)
The definition of 'Math.max' in that specification.
Draft

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