Can you pass default values to a class constructor? Here, last returns undefined.
class greatFunction {
options: {
names: {first: 'Joe', last: 'Bloggs'}
}
constructor(options) {
console.log(options.names.first + ' ' + options.names.last);
}
}
Called:
new greatFunction({
names: {
first: 'Paul'
}
});
instead of doing that why dont you create an interface like this
interface names {
firstname:string;
lastname ?: string;
}
Since you can't create make a property of a parameter optional.
Or you do the hard way which is like this
interface IOptions{
names:INames;
}
interface INames {
first:string;
last?:string;
}
class greatFunction{
constructor (options:IOptions){
options.names.last = options.names.last?options.names.last:'Default';
console.log(options.names.first + ' ' + options.names.last)
}
}
new greatFunction({names:{first:'Theophilus'}});
It should return the default in console
Try setting default values:
class GreatFunction {
options: {
names: {first: 'Joe', last: 'Bloggs'}
}
constructor({names: {first=this.options.names.first: firstName, last=this.options.names.last: lastName}}) {
console.log(`${firstName} ${lastName}`)
}
}
Alternatively, use a library, for example lodash.defaults() seems to fit your use case.
constructor({first=this.options.first, last=this.options.last}) { console.log(first + ' ' + last)}You do need to pass something to the function, so one option would be to try something like this:
class greatFunction {
defaultOptions = {
names: { first: 'Joe', last: 'Bloggs' }
}
constructor(options) {
if (options == null)
options = this.defaultOptions;
console.log(options.names.first + ' ' + options.names.last);
}
}
You can then create a new greatFunction using:
let x = new greatFunction(null)
Or:
let y = new greatFunction({ names: { first: 'Test', last: 'Blah' } });
Alternatively, don't do it using the constructor, and use a property after initialising. For example:
class greatFunction {
public options = {
names: { first: 'Joe', last: 'Bloggs' }
}
constructor() { }
doSomething() {
console.log(this.options.names.first + ' ' + this.options.names.last);
}
}
and then use with:
let x = new greatFunction();
x.options = { names: { first: 'Test', last: 'Blah' } };
x.doSomething();
options.names.last = options.name.last || "default"if the first side of the check (left from||) is true, that value is taken, if it is false, the right side is taken. Since undefined is false, it defaults to"default"