\[ \begin{flalign} A=\left[\ 1,2,3,4,7\ \right]&& \end{flalign} \] \[ \begin{flalign} B=\left[\ 4,5,6,7,8\ \right]&& \end{flalign} \] \[ \begin{flalign} C=\operatorname{sort}\left(\operatorname{unique}\left(\operatorname{join}\left(B,A\right)\right)\right)　　\color{Green}← A \cup B&& \end{flalign} \] \[ \begin{flalign} D=\operatorname{unique}\left(\operatorname{join}\left(B,A\right)\right)\left[\operatorname{count}\left(B\right)+1...\right]&& \end{flalign} \] \[ \begin{flalign} E=\operatorname{sort}\left(A\left[\operatorname{count}\left(D\right)+1...\right]\right)　　\color{Green}← A \cap B&& \end{flalign} \]
コピペ用テキストエリア（ Ctrl＋v で貼り付け ）：

A=\left[\ 1,2,3,4,7\ \right] B=\left[\ 4,5,6,7,8\ \right] C=\operatorname{sort}\left(\operatorname{unique}\left(\operatorname{join}\left(B,A\right)\right)\right) D=\operatorname{unique}\left(\operatorname{join}\left(B,A\right)\right)\left[\operatorname{count}\left(B\right)+1...\right] E=\operatorname{sort}\left(A\left[\operatorname{count}\left(D\right)+1...\right]\right)

　※ 参照： JavaScript ＞ JavaScript＿算数 ＞ \( A \cup B\ A \cap B \) の要素を書き出す