void setUint8(
int byteOffset,
int value
)

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

In other words, value must be between 0 and 255, 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
 * unsigned binary representation of the specified [value], which must fit
 * in a single byte.
 *
 * In other words, [value] must be between 0 and 255, inclusive.
 *
 * Throws [RangeError] if [byteOffset] is negative,
 * or greater than or equal to the length of this object.
 */
void setUint8(int byteOffset, int value);