We have found that the later years of John were passed in Asia Minor and principally at Ephesus. Irenæus, who had such excellent sources of information and who was himself educated in the same region by a disciple of John, declares that the Gospel was written at Ephesus; with him agree Jerome and later writers. Irenæus also states that it was the latest written of the Gospels, and this agrees with judgment of all commentators. It was therefore written after the departure of the Apostle to this portion of the world, and there can be little doubt that its place of composition was the great metropolis of this portion of the world, and for along period after the fall of Jerusalem, the chief center of Christianity. "After the destruction of Jerusalem Ephesus became the center of Christian life in the East. Even Antioch, the original source of missions to the Gentiles, and the future metropolis of the Christian patriarch, appears for a time less conspicuous in the obscurity of early church history than Ephesus, to which Paul inscribed his Epistle, and in which John found a dwelling place and a tomb. This half Greek, half Oriental city, visited by ships from all parts of the Mediterranean, and united by great roads with the markets of the interior, was the common meeting place of various characters and classes of men." -- Conybeare and Howson.

Of the date we can have no certain knowledge. There are internal evidences that would refer it to the last quarter of the first century. It has been held by some critics that it is the last composition of the New Testament, but I think it contains internal evidence that it was composed before Revelation, while the latter seems in its final words to close the sacred canon. In addition, the voice of the early church agrees that the Gospel had the earlier date. It was almost certainly composed between A. D.75 and A. D.90. A vague tradition that it was written during the exile to Patmos has no authority. Alford fixes the date between A. D.70 and 85; Macdonald at A. D.86 or 86; Godet between A. D.80 and 90; Tholuck at not far from A. D.100.