字符右补白

pad.md

'use strict'

// 兼容模式，兼容老版本浏览器
function pad(value, length, placeholder) {
  length = length || 15;
  placeholder = placeholder || ' ';

  var diff = Math.max(0, length - value.length) + 1;

  return value + new Array(diff).join(placeholder);
}

// 流行模式，只兼容现代浏览器（es5, es6）
function pad(value, length, placeholder) {
  length = length || 15;
  placeholder = placeholder || ' ';
  
  var diff = Math.max(0, length - value.length);

  return value + placeholder.repeat(diff);
}

// 现代模式，只兼容现代浏览器（es6）
function pad(value, length = 15, placeholder = ' ') {
  var diff = Math.max(0, length - value.length);

  return value + placeholder.repeat(diff);
}