How does the author use foreshadowing in In Dubious Battle?

In Chapter Eight, the deputies’ knowledge of the strikers’ plan to sneak out of camp before daylight is foreshadowed by Mac’s insistence Dakin not tell the men about the plan in advance because there are probably spies among them. Jim and Mac’s “capture” by the deputies is foreshadowed by Mac’s cautioning Jim to be ready to “cut for the camp and yell like hell” if anything seems suspicious.