In this paper, the chaotic behaviours in the real and complex dynamics of ζ λ (z) = λ z z+1 e −z , λ > 0, z ∈ C are investigated. The bifurcation in the dynamics of ζ λ (x), x ∈ R \ {−1}, occurs at several parameter values and the dynamics becomes chaotic when the parameter λ crosses certain values. The Lyapunov exponent of ζ λ (x) is computed for quantifying the chaos. The characterization of the Julia set of ζ λ (z) as complement of the basin of attraction is found and is applied to computationally simulate the images of the Julia sets. Finally, the results on the dynamics of ζ λ (z) are compared with the known results.