How to implement a system like on kickstarter?

Question

Crowdfunding

Interested in how to implement so that the money that a person donated to something is debited only when the required amount is reached in the project (for example, the project needs $ 1000. One put $ 700 at the beginning of the project and the other at the end $ 300. Since the amount is equal, only then the money are translated).

Answer 1

Use the payment system API to check the balance

Answer 2

if (enoughMoney){
sendThemToThisFraud(projectId, fraudId)
}