ducha-qianduan/node_modules/svg-sprite-loader/runtime/browser-sprite.js

import BrowserSprite from 'svg-baker-runtime/src/browser-sprite';
import domready from 'domready';

const spriteNodeId = '__SVG_SPRITE_NODE__';
const spriteGlobalVarName = '__SVG_SPRITE__';
const isSpriteExists = !!window[spriteGlobalVarName];

// eslint-disable-next-line import/no-mutable-exports
let sprite;

if (isSpriteExists) {
  sprite = window[spriteGlobalVarName];
} else {
  sprite = new BrowserSprite({
    attrs: {
      id: spriteNodeId,
      'aria-hidden': 'true'
    }
  });
  window[spriteGlobalVarName] = sprite;
}

const loadSprite = () => {
  /**
   * Check for page already contains sprite node
   * If found - attach to and reuse it's content
   * If not - render and mount the new sprite
   */
  const existing = document.getElementById(spriteNodeId);

  if (existing) {
    sprite.attach(existing);
  } else {
    sprite.mount(document.body, true);
  }
};

if (document.body) {
  loadSprite();
} else {
  domready(loadSprite);
}

export default sprite;