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What is DataView.getFloat32() in JavaScript?

Abdul Monum

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The DataView.prototype.getFloat32() is a method in JavaScript that gets a signed 32-bit float value at the specified byte offset from the start of the DataView object.

Syntax

The syntax of the method is as follows:


getFloat32(byteOffset : Number, [littleEndian = false : Boolean]) : Number

Parameters

  • byteOffset: A Number specifying the byte offset from the start of the view.

  • littleEndian: An optional parameter specifying whether the 32-bit float that is retrieved should be interpreted in the little-endian format or the big-endian format.


By default, the value is False, which means a big-endian value is stored.

Binary data in JavaScript and the DataView class

While many languages provide byte arrays to manipulate binary data, things work differently in JavaScript.

The most fundamental binary object in JavaScript is the ArrayBuffer, which stores a reference to a fixed-length contiguous memory space that contains a raw sequence of bytes.

However, to interpret and manipulate the ArrayBuffer, we need something called view objects.

View objects

View objects themselves do not store any data, but rather provide the different interfaces to read and write byte data in the raw buffer.

The DataView class is one such view over the ArrayBuffer that provides flexibility in interpreting the buffer.

By using DataView objects, we can access the data in any format we like and at any offset. Moreover, the format in which data is interpreted is done at the method call time.

Syntax of DataView

The syntax to declare a DataView object is as follows:


new DataView(buffer, [byteOffset], [byteLength])

  • buffer: The ArrayBuffer object containing the raw sequence of bytes.

  • byteOffset: The starting byte position of the view from the starting position of ArrayBuffer. The default value is 0.

  • byteLength: The byte length that will be viewed from the specified byteOffset. By default, the whole buffer is viewed.

Now we have some idea of binary data in JavaScript and declaring DataView objects.

Code

Let’s look at how can we use dataView.getFloat32() in a program:

const buffer = new ArrayBuffer(16);
const view = new DataView(buffer);
view.setFloat32(1, Math.E);
console.log(view.getFloat32(1));

Explanation

  • In the example above, we declare an ArrayBuffer with length of 12 bytes.

  • We create the object dataView using the constructor of the DataView class and passing the buffer object to it.

  • By using the dataView.setFloat32(1, Math.E) function call, we store the value of Euler’s Constant in the 32 bits after the first byte from the start of the view.

  • By using the dataView.getFloat32(1) method, we verify that the value has been set successfully in the buffer.

RELATED TAGS

javascript
communitycreator
dataview
getfloat32

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

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