Mastering TypeScript 3 - Third Edition

Spread precedence

When using object spread, properties will be copied incrementally. In other words, if two objects both have a property with the same name, then the object property that was specified last will take precedence. As an example of this, consider the following code:

let objPrec1 = { id: 1, name: "object prec 1" }; 
let objPrec2 = { id: 1001, description: "object prec 2 descripton" } 
 
let obj4 = { ...objPrec1, ...objPrec2 }; 
console.log(`obj4 : ${JSON.stringify(obj4)}`); 

Here, we have defined two objects named objPrec1 and objPrec2. Note that both have an id property, but objPrec1 has a name property, and objPrec2 has a description property. As we have already seen, the rest and spread syntax will combine the properties of both ...