6. 字符串

6.1 字符串使用单引号 '' 。

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

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

6.2 字符串超过 80 个字节应该使用字符串连接号换行。

6.3 注：过度使用字串连接符号可能会对性能造成影响。jsPerf 和讨论.

// 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 程序化生成字符串时，使用模板字符串代替字符串连接。

为什么？模板字符串更为简洁，更具可读性。

  // 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}?`;
  }