程式化的控制台记录

Question

当我在Facebook上并打开控制台时,我在下面看到这张图片.他们如何做到这一点？

Answer 1

就像在Firebug中一样,您可以使用%c样式控制台日志输出.看看我们如何实现Facebook的例子:

console.log("%cStop!", "color: red; font-family: sans-serif; font-size: 4.5em; font-weight: bolder; text-shadow: #000 1px 1px;");

由于它支持CSS属性,我们甚至可以在那里"绘制"图像:

(function(url) {
  // Create a new `Image` instance
  var image = new Image();

  image.onload = function() {
    // Inside here we already have the dimensions of the loaded image
    var style = [
      // Hacky way of forcing image's viewport using `font-size` and `line-height`
      'font-size: 1px;',
      'line-height: ' + this.height + 'px;',

      // Hacky way of forcing a middle/center anchor point for the image
      'padding: ' + this.height * .5 + 'px ' + this.width * .5 + 'px;',

      // Set image dimensions
      'background-size: ' + this.width + 'px ' + this.height + 'px;',

      // Set image URL
      'background: url('+ url +');'
     ].join(' ');

     // notice the space after %c
     console.log('%c ', style);
  };

  // Actually loads the image
  image.src = url;
})('https://i.cloudup.com/Zqeq2GhGjt-3000x3000.jpeg');