js简单优化之大量 if/switch判断

场景

const title = 0;

    if (title == 1) {
        console.log(1);
    }else if(title == 2){
        console.log(2);
    }else if(title == 3){
        console.log(3);
    }else if(title == 4){
        console.log(4);
    }
    ………………
    switch (title) {
        case 1:
            console.log(1);
            break;
        case 2:
            console.log(2);
            break;
        case 3:
            console.log(3);
            break;
        case 4:
            console.log(4);
            break;
    }
    ……

优化

    const actions = {
        1: [1, 11],
        2: [2, 22],
        3: [3, 33],
        4: [4, 44],
    }
    if (actions[title]) {
        console.log(actions[title][0]);
        alert(actions[title][1]);
    }

//es6  Map方法
    const actions = new Map([
        [1, [1, 11]],
        [2, [2, 22]],
        [3, [3, 33]],
        [4, [4, 44]],
        ['default', [0, '00']]
    ])
    const myfunction = (title) => {
        let action = actions.get(title) || actions.get('default')
        console.log(action[0])
        console.log(action[1])
    }
    myfunction(title)