If there be no assessment for benefits in any of the contracting municipalities, the body or board of each municipality having charge of its finances may issue the bonds of such municipality to an amount sufficient to defray its part, share or percentage of all the costs, damages and expenses of the said improvements, or of any contract relating thereto, entered into by it jointly with the other contracting municipalities, pursuant to the provisions of this article, regard being had to the bonds already issued for completed improvements, and to the bonds which will probably be required for improvements actually contemplated, but not yet authorized to be issued.