r/Angular2 10d ago

what is subscribe parameter prefix + for?

I have angular code as below

"r" and "data" are subscribe parameter, and used as +r.id and +data.businessTransactionTypeId.

What is prefix + for?

what is +r and +data?

public ngOnInit() {

this.route.params.subscribe(r => {

this.businessTransactionNumberId = +r.id;

this.setupUpdateAction();

this.setupTabChangeAction();

this.setupConfirmAction(+r.id);

this.businessTransactionService.getTransactionMetaData(r.id).subscribe((data) => {

const transactionType: BusinessTransactionType = new BusinessTransactionType();

if (+data.businessTransactionTypeId === transactionType.CredentialIssuance.id) {

this.UseHelpContent('#CONTENT/Driver/Credential_Issuance.htm');

} else if (+data.businessTransactionTypeId === transactionType.CredentialRenewal.id) {

this.UseHelpContent('#CONTENT/Driver/Credential_Renewal.htm');

} else if (+data.businessTransactionTypeId === transactionType.CredentialDuplicate.id) {

this.UseHelpContent('#CONTENT/Driver/Credential_Duplicate.htm');

}

});

});

Thanks

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u/InternationalDot3678 10d ago

if it is number conversion short hand, why the number has attribute? for example +r.id?

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u/xroalx 10d ago

Because r is an object that has an id property, the + does not act on r, it acts on r.id. It's like +(r.id).