code: def test_js_code():
      fn = "function() { console.log('test_js_code') }"
      js_code = utils.JsCode(fn)
      assert_equal(
          js_code.js_code, "--x_x--0_0--{}--x_x--0_0--".format(fn)
      )
  
imports: from nose.tools import assert_equal
  from pyecharts.commons import utils
  from pyecharts.datasets import EXTRA
label_desc: Use image node_id 3 for calling a global function with example usage: test_js_code() without return types