void setInt8(
int byteOffset,
int value
)

Sets the byte at the specified byteOffset in this object to the two's complement binary representation of the specified value, which must fit in a single byte.

In other words, value must be between -128 and 127, inclusive.

Throws RangeError if byteOffset is negative, or greater than or equal to the length of this object.

Source

/**
 * Sets the byte at the specified [byteOffset] in this object to the
 * two's complement binary representation of the specified [value], which
 * must fit in a single byte.
 *
 * In other words, [value] must be between -128 and 127, inclusive.
 *
 * Throws [RangeError] if [byteOffset] is negative, or
 * greater than or equal to the length of this object.
 */
void setInt8(int byteOffset, int value);