code: function isAssignmentExpression(expression) {
  
      var left;
  
      left = expression.left;
      return expression.type === 'AssignmentExpression' && left && left.type === 'Identifier';
  
  }
docs: 判断当前语句是否为赋值
  @param expression
  @returns {boolean|*|Function|left|jQuery.offset.left|jQuery.position.left|testFixture.expression.left.left|testFixture.expression.left|testFixture.expression.right.value.body.expression.left|testFixture.expression.right.left|testFixture.expression.test.left|testFixture.test.left|testFixture.init.left|testFixture.left|testFixture.left.init.body.argument.left|testFixture.expression.body.argument.left|testFixture.body.expression.left|testFixture.argument.left|parentOffset.left|.runtimeStyle.left|node.style.left|pos.left|elem.runtimeStyle.left|elem.style.left|props.left|parentOffset.left|boolean}