dist/flow.js
function (file) {
      var custom = this.opts.generateUniqueIdentifier;
      if (typeof custom === 'function') {
        return custom(file);
      }
      // Some confusion in different versions of Firefox
      var relativePath = file.relativePath || file.webkitRelativePath || file.fileName || file.name;
      return file.size + '-' + relativePath.replace(/[^0-9a-zA-Z_-]/img, '');
    }
function (file) {
      var custom = this.opts.generateUniqueIdentifier;
      if (typeof custom === 'function') {
        return custom(file);
      }
      // Some confusion in different versions of Firefox
      var relativePath = file.relativePath || file.webkitRelativePath || file.fileName || file.name;
      return file.size + '-' + relativePath.replace(/[^0-9a-zA-Z_-]/img, '');
    }
Generate unique identifier for a file
@function
@param {FlowFile} file
@returns {string}