Huddersfield striker Jordan Rhodes scored two first-half goals to keep his side in the hunt for automatic promotion following their eighth win in 10 matches.
Rhodes took his tally to 22 goals for the season by netting a tap-in and then scoring with a glancing header.
Benik Afobe created the opener in the nine minute by dispossessing Will Antwi as the Dagenham defender tried to shepherd the ball out of play. Afobe then squared the ball for Rhodes to score from close range.
The visitors, who have now lost seven of their last eight games, hit back in the 28th minute when Romain Vincelot blasted into the top left corner after playing a neat one-two on the edge of the box with John Akinde.
But they were only level for four minutes as Rhodes ran from deep to glance in Gary Roberts's cross swung in from the left.
Afobe missed three good chances in the first half and it nearly proved costly as Dagenham rallied after the break.
The visitors nearly almost equalised in the 72nd minute when Akinde's shot hit the post and then rebounded back to him. Town keeper Ian Bennett made a brilliant save to deny the striker a goal at the second attempt.
Peter Gain and substitute DJ Green both fired wide late on as the Daggers searched in vain for an equaliser.
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