Float64Array - JavaScript 编辑

The Float64Array typed array represents an array of 64-bit floating point numbers (corresponding to the C double data type) in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).

Constructor

Float64Array()

Creates a new Float64Array object.

Static properties

Float64Array.BYTES_PER_ELEMENT

Returns a number value of the element size. 8 in the case of an Float64Array.

Float64Array.name

Returns the string value of the constructor name. In the case of the Float64Array type: "Float64Array".

Static methods

Float64Array.from()

Creates a new Float64Array from an array-like or iterable object. See also Array.from().

Float64Array.of()

Creates a new Float64Array with a variable number of arguments. See also Array.of().

Instance properties

Float64Array.prototype.buffer

Returns the ArrayBuffer referenced by the Float64Array Fixed at construction time and thus read only.

Float64Array.prototype.byteLength

Returns the length (in bytes) of the Float64Array from the start of its ArrayBuffer. Fixed at construction time and thus read only.

Float64Array.prototype.byteOffset

Returns the offset (in bytes) of the Float64Array from the start of its ArrayBuffer. Fixed at construction time and thus read only.

Float64Array.prototype.length

Returns the number of elements hold in the Float64Array. Fixed at construction time and thus read only.

Instance methods

Float64Array.prototype.copyWithin()

Copies a sequence of array elements within the array. See also Array.prototype.copyWithin().

Float64Array.prototype.entries()

Returns a new Array Iterator object that contains the key/value pairs for each index in the array. See also Array.prototype.entries().

Float64Array.prototype.every()

Tests whether all elements in the array pass the test provided by a function. See also Array.prototype.every().

Float64Array.prototype.fill()

Fills all the elements of an array from a start index to an end index with a static value. See also Array.prototype.fill().

Float64Array.prototype.filter()

Creates a new array with all of the elements of this array for which the provided filtering function returns true. See also Array.prototype.filter().

Float64Array.prototype.find()

Returns the found value in the array, if an element in the array satisfies the provided testing function or undefined if not found. See also Array.prototype.find().

Float64Array.prototype.findIndex()

Returns the found index in the array, if an element in the array satisfies the provided testing function or -1 if not found. See also Array.prototype.findIndex().

Float64Array.prototype.forEach()

Calls a function for each element in the array. See also Array.prototype.forEach().

Float64Array.prototype.includes()

Determines whether a typed array includes a certain element, returning true or false as appropriate. See also Array.prototype.includes().

Float64Array.prototype.indexOf()

Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found. See also Array.prototype.indexOf().

Float64Array.prototype.join()

Joins all elements of an array into a string. See also Array.prototype.join().

Float64Array.prototype.keys()

Returns a new Array Iterator that contains the keys for each index in the array. See also Array.prototype.keys().

Float64Array.prototype.lastIndexOf()

Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found. See also Array.prototype.lastIndexOf().

Float64Array.prototype.map()

Creates a new array with the results of calling a provided function on every element in this array. See also Array.prototype.map().

Float64Array.prototype.reduce()

Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value. See also Array.prototype.reduce().

Float64Array.prototype.reduceRight()

Apply a function against an accumulator and each value of the array (from right-to-left) as to reduce it to a single value. See also Array.prototype.reduceRight().

Float64Array.prototype.reverse()

Reverses the order of the elements of an array — the first becomes the last, and the last becomes the first. See also Array.prototype.reverse().

Float64Array.prototype.set()

Stores multiple values in the typed array, reading input values from a specified array.

Float64Array.prototype.slice()

Extracts a section of an array and returns a new array. See also Array.prototype.slice().

Float64Array.prototype.some()

Returns true if at least one element in this array satisfies the provided testing function. See also Array.prototype.some().

Float64Array.prototype.sort()

Sorts the elements of an array in place and returns the array. See also Array.prototype.sort().

Float64Array.prototype.subarray()

Returns a new Float64Array from the given start and end element index.

Float64Array.prototype.values()

Returns a new Array Iterator object that contains the values for each index in the array. See also Array.prototype.values().

Float64Array.prototype.toLocaleString()

Returns a localized string representing the array and its elements. See also Array.prototype.toLocaleString().

Float64Array.prototype.toString()

Returns a string representing the array and its elements. See also Array.prototype.toString().

Float64Array.prototype[@@iterator]()

Returns a new Array Iterator object that contains the values for each index in the array.

Examples

Different ways to create a Float64Array

// From a length
var float64 = new Float64Array(2);
float64[0] = 42;
console.log(float64[0]); // 42
console.log(float64.length); // 2
console.log(float64.BYTES_PER_ELEMENT); // 8

// From an array
var arr = new Float64Array([21,31]);
console.log(arr[1]); // 31

// From another TypedArray
var x = new Float64Array([21, 31]);
var y = new Float64Array(x);
console.log(y[0]); // 21

// From an ArrayBuffer
var buffer = new ArrayBuffer(32);
var z = new Float64Array(buffer, 0, 4);

// From an iterable
var iterable = function*(){ yield* [1,2,3]; }();
var float64 = new Float64Array(iterable);
// Float64Array[1, 2, 3]

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• JavaScript typed arrays
• ArrayBuffer
• DataView