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JavaScript DataView setFloat64() Method

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The JavaScript DataView setFloat64() method is used to store a 64-bit floating point number in the 8 bytes (where 1 byte = 8 bits) starting at the specified byte offset within this DataView. It is possible to store multiple byte values at any byte offset within the specified bounds.

A floating point number is a positive or negative whole number with a decimal point. For example, 5.5, 0.25, -103.342, etc.

If the value of the byteOffset parameter falls outside the bounds of the data view, it will throw a 'RangeError' exception.

Syntax

Following is the syntax of the JavaScript DataView setFloat64() method −

setFloat64(byteOffset, value, littleEndian)

Parameters

This method accepts three parameters named 'byteOffset', 'value', and 'littleEndian', which are described below −

  • byteOffset − The position in the DataView where the byte will be stored.
  • value − A 32-bit floating point number that needs to be stored.
  • littleEndian − It indicates whether the data is stored in little-or-big endian format.

Return value

This method returns 'undefined'.

Example 1

The following is the basic example of the JavaScript DataView setFloat64() method.

<html>
<body>
<script>
   const buffer = new ArrayBuffer(16);
   const data_view = new DataView(buffer);
   const byteOffset = 0;
   const value = 433.45;
   document.write("The byte offset: ", byteOffset);
   document.write("<br>Value: ", value);
   //using setFloat64() method
   document.write("<br>The setFloat64() method: ", data_view.setFloat64(byteOffset, value));
</script>
</body>
</html>

Output

The above program returns 'undefined' −

The byte offset: 0
Value: 433.45
The setFloat64() method: undefined

Example 2

The following is another example of the JavaScript DataView setFloat64() method. We use this method to store 64-bit floating point number (retrieve from) Math.PI starting at the specified byte 1 within this DataView.

<html>
<body>
<script>
    const buffer = new ArrayBuffer(16);
    const data_view = new DataView(buffer);
    const byteOffset = 1;
    const value = Math.PI;
    document.write("The byte offset: ", byteOffset);
    document.write("<br>Value: ", value);
    //using setFloat64() method
   data_view.setFloat64(byteOffset);
   document.write("<br>The store value: ", data_view.getFloat64(byteOffset, value));
</script>
</body>
</html>

Output

After executing the above program, it will store the specified floating point number within the DataView and display it as −

The byte offset: 1
Value: 3.141592653589793
The store value: 3.143e-319

Example 3

If the value of the byteOffset parameter falls outside the bounds of this data view, it will throw a 'RangeError' exception.

<html>
<body>
<script>
   const buffer = new ArrayBuffer(16);
   const data_view = new DataView(buffer);
   const byteOffset = -1;
   const value = 16.34;
   document.write("The byte offset: ", byteOffset);
   document.write("<br>Value: ", value);
   try {
      //using setFloat64() method
      data_view.setFloat64(byteOffset);
   } catch (error) {
      document.write("<br>", error);
   }
</script>
</body>
</html>

Output

Once the above program is executed, it will throw a 'RangeError' exception as −

The byte offset: -1
Value: 16.34
RangeError: Offset is outside the bounds of the DataView
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