console 命令行工具 X clear

console

document.querySelector('input').addEventListener('change', ()=>{
  var reader = new FileReader();
  reader.readAsDataURL(document.querySelector('input').files[0]); reader.onload = function() {  alert(atob(this.result.replace('data:text/plain;base64,','')));
  }
})

<input type="file" />