String Back

1. Use single qutoes for string

• To use single quotes '' for strings.
• Eslint rules tags: quotes

/**
 * bad
 */
const name = "PuiMan Cheui";

/**
 * good
 */
const name = 'PuiMan Cheui';

2. Multiple lines when too many characters

• Strings that cause the line to go over 100 characters should be written across multiple lines using string concatenation.
• Note that: if overused, long strings with concatenation could impact performance. jsPerf & Discussion.

/**
 * 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.';

/**
 * you can also use template string
 */
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.`;

3. Use template strings

• When programmatically building up strings, use template strings instead of concatenation.

the reason is that template strings give you a readable, concise(簡練的) syntax with proper newlines and string interpolation(內插) features.

/**
 * 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}?`;
}

• Notice that: template strings are only supported by ECMAScript 6 (ES6). Browser Compatibility

4. Do not use eval()

• It's not recommended to use eval() on a string, cause it will open too many vulnerabilities(弱點).