javascript函数工具有哪些（如何让你的JavaScript函数更加优雅详解）

const greet = (obj) => {
  return `${obj.greeting}, ${obj.firstName}${obj.lastName}`;
}

const greet = ({
  greeting,
  firstName,
  lastName
}) => {
  return `${greeting}, ${firstName}${lastName}`;
}

const arr = [1, 2, 3].map(a => a * 2);

const double = a => a * 2;
const arr = [1, 2, 3].map(double);

if (score === 100 || remainingPlayers === 1 || remainingPlayers === 0) {
    quitGame();
  }

const winnerExists = () => {
  return score === 100 ||
    remainingPlayers === 1 ||
    remainingPlayers === 0
}
if (winnerExists()) {
  quitGame();
}

const getValue = (prop) => {
  switch (prop) {
    case 'a': {
      return 1;
    }
    case 'b': {
      return 2;
    }
    case 'c': {
      return 3;
    }
  }
}
const val = getValue('a');

const obj = {
  a: 1,
  b: 2,
  c: 3
}
const val = obj['a'];

const map = new Map([['a', 1], ['b', 2], ['c', 3]])
const val = map.get('a')

const menuConfig = {
  title: null,
  body: 'Bar'
};
function createMenu(config) {
  config.title = config.title || 'Foo';
  config.body = config.body || 'Bar';
}
createMenu(menuConfig);

const menuConfig = {
  title: 'Order',
  body: 'Send'
};
function createMenu(config) {
  config = Object.assign({
    title: 'Foo',
    body: 'Bar'
  }, config);
  // config : {title: "Order", body: "Bar"}
  // ...
}
createMenu(menuConfig);

var paging = function( currPage ){
    if ( currPage <= 0 ){
        currPage = 0;
        jump( currPage );    // 跳转
    }else if ( currPage >= totalPage ){
        currPage = totalPage;
        jump( currPage );    // 跳转
    }else{
        jump( currPage );    // 跳转
    }
};

var paging = function( currPage ){
    if ( currPage <= 0 ){
        currPage = 0;
    }else if ( currPage >= totalPage ){
        currPage = totalPage;
    }
    jump( currPage );    // 把jump函数独立出来
};

var getUserInfo = function(){
    ajax( 'http:// xxx.com/userInfo', function( data ){
        console.log( 'userId: ' + data.userId );
        console.log( 'userName: ' + data.userName );
        console.log( 'nickName: ' + data.nickName );
    });
};

var getUserInfo = function(){
    ajax( 'http:// xxx.com/userInfo', function( data ){
        printDetails( data );
    });
};

var printDetails = function( data ){
    console.log( 'userId: ' + data.userId );
    console.log( 'userName: ' + data.userName );
    console.log( 'nickName: ' + data.nickName );
};