計算の条件分岐のコード　リファクタリング

calc.js

  function keisan(agent) {
	let　num1 = agent.parameters["number"][0];
    let　num2 = agent.parameters["number"][1];
  	let calc	= agent.parameters["calc"];
    
    if (calc == "加算"){
		let num3 = num1 + num2;
		agent.add( num1 + "と" + num2 + "を足すと" + num3 + "です");           
	} else if(calc ==　"減算"){
		let num3 = num1 - num2;
		agent.add( num1 + "から" + num2 + "を引くと" + num3 + "です");
	} else if (calc	==　"乗算"){
		let num3 = num1 * num2;
		agent.add( num1 + "と" + num2 + "をかけると" + num3 + "です");
	} else if (calc	==　"徐算"){
		let num3 = num1 / num2;
		agent.add( num1 + "を" + num2 + "で割ると" + num3 + "です");
	}
  }  

calc_fix.js

  function keisan(agent) {
    let num1 = agent.parameters["number"][0];
   	let num2 = agent.parameters["number"][1];
   	let calc = agent.parameters["calc"];
	let num3 = "";
    
    if (calc == "加算"){
		num3 = num1 + num2;
	} else if(calc == "減算"){
	  	num3 = num1 - num2;
	} else if (calc	== "乗算"){
	  	num3 = num1 * num2;
	} else if (calc	== "徐算"){
      	num3 = num1 / num2;
	}
	agent.add( "計算結果は"+ num3 + "です");
  }

calc_fix2.js

  function keisan(agent) {
  	let num1 = agent.parameters["number"][0];
    let num2 = agent.parameters["number"][1];
    let calc = agent.parameters["calc"];
	let num3 = calculation(num1, num2, calc);
    
    agent.add( "計算結果は"+ num3 + "です");
  }
  
  function calculation(num1, num2, calc){
    if (calc == "加算"){
    		return num1 + num2;
	}	else if(calc == "減算"){
    		return num1 - num2;
	}	else if (calc	== "乗算"){
      		return num1 * num2;
	}	else if (calc	== "徐算"){
      		return num1 / num2;
	}
  }