terminal进度条

loading.js

const readline = require('readline');

// 百分比
let percentage = 0;
// 时长
let time = 5 * 1000;
// 频率
let frequency = 50;
// 步长
let step = 1 / (time / frequency);
// 总长度（50字节）
let length = 50;
// 字符
let char = '▪';

const resetScreen = () => {
  readline.cursorTo(process.stdout, 0, 0);
  readline.clearScreenDown(process.stdout);
  readline.clearLine(process.stdout);
};

const print = size => {
  process.stdout.write(`[${char.repeat(size) + ' '.repeat(length - size)}]\n`);
};

const t = () => {
  if (percentage >= 1) {
    process.stdout.write('doen!');
    return;
  }

  percentage += step;
  let size = Math.floor(length * percentage);
  resetScreen();
  print(size);
  setTimeout(t, frequency);
};

t();