6. 字符串

6.1?字符串使用單引號?''?。

// bad
const name = "Capt. Janeway";

// good
const name = 'Capt. Janeway';

6.2?字符串超過 80 個字節(jié)應(yīng)該使用字符串連接號換行。

6.3?注：過度使用字串連接符號可能會對性能造成影響。jsPerf?和?討論.

// bad
const errorMessage = 'This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast.';

// bad
const errorMessage = 'This is a super long error that was thrown because \
of Batman. When you stop to think about how Batman had anything to do \
with this, you would get nowhere \
fast.';

// good
const errorMessage = 'This is a super long error that was thrown because ' +
  'of Batman. When you stop to think about how Batman had anything to do ' +
  'with this, you would get nowhere fast.';

6.4?程序化生成字符串時，使用模板字符串代替字符串連接。

為什么？模板字符串更為簡潔，更具可讀性。

  // bad
  function sayHi(name) {
    return 'How are you, ' + name + '?';
  }

  // bad
  function sayHi(name) {
    return ['How are you, ', name, '?'].join();
  }

  // good
  function sayHi(name) {
    return `How are you, ${name}?`;
  }