DataView.prototype.setBigInt64()

The setBigInt64() method stores a signed 64-bit integer (long long) value at the specified byte offset from the start of the DataView.

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setBigInt64(byteOffset, value)
setBigInt64(byteOffset, value, littleEndian)

byteOffset: The offset, in bytes, from the start of the view to store the data from.
value: The value to set as a BigInt. The highest possible value that fits in a signed 64-bit integer is 2n ** (64n -1n) - 1n (9223372036854775807n). Upon overflow, it will be negative (-9223372036854775808n).
littleEndian: Optional Indicates whether the 64-bit int is stored in little- or big-endian format. If false or undefined, a big-endian value is written.

RangeError: Thrown if the byteOffset is set such that it would store beyond the end of the view.

var buffer = new ArrayBuffer(8);
var dataview = new DataView(buffer);
dataview.setBigInt64(0, 3n);
dataview.getBigInt64(0); // 3n

Specification
ECMAScript Language Specification # sec-dataview.prototype.setbigint64

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