例1 function add(x,y){return x+y;} function sub(x,y){return x-y;} //上記関数のいずれか1つを呼び出す関数 function operate(operator, operand1, operand2){ return operator(operand1, operand2); } //関数operateで(2+5)+(5-1)を計算 var i = operate…