My script is
$scope.uid = '';
this.myService.getCount(response).then(function (value) {
$scope.uid = value;
});
I want value outside of this promise but I am getting error Cannot find name '$scope'
Have you try to have uid as a class member and if you shoud use outside your class scope you can define it as a static member.
If it is will not help you please provide more detailed information
class YourClass {
static uid: string = '';
static YourClassFunc() {
this.myService.getCount(response).then(function (value) {
YourClassFunc.uid = value;
});
}
}
https://www.tutorialsteacher.com/typescript/typescript-static
Related
I need to dynamically update the fields of this class dynamically with an object
export default class Foo {
private accessKey: string;
private workspaceId: string;
private api: AxiosInstance;
public bar: string;
public name: string;
...
...
private async fetch() {
try {
// data contains bar and name value
const { data } = await this.api.get("/");
// goal
this = {...this, ...data};
See goal comment, how can I do this dynamically?
Assignments and this
Why assigning to this is disallowed
Disregarding that it's not allowed, you don't want to reassign your this reference.
If it was allowed, we could write this confusing code:
const object = {
reassignSelf() {
this = {};
}
};
const ref = object;
object.reassignSelf();
/* Both ref and object are constant variables,
* so their values (references) should never change.
* But by reassigning `this` in object.reassignSelf,
* what value should this comparison produce?
*/
console.log(ref === object);
Then how to assign to this?
As implied earlier, we don't want to reassign this; we want to reassign its properties:
Static assignment. Example:
this.bar = data.bar;
this.name = data.name;
Dynamic assignment. Example:
Object.assign(this, data);
Use Object.assign
class X {
update(from: Partial<this>) {
Object.assign(this)
}
}
some times code says it best. In below example code in Chain.add I have the function name and vars fed in to it. But I am trying to reference the object that the function is associated with. How can I do this
class Chainable {
constructor(...values) {
this._chainableConstruct={
name: this.constructor.name,
values
};
}
}
class Chain {
constructor() {
this.data=[];
}
add(func,vars) {
console.log(func.name); //returns fun
console.log(...vars); //returns test 45
console.log(func.parent); //return undefined want object t from line 28
}
}
class Test extends Chainable {
fun() {
console.log("fun");
}
}
let t=new Test();
let c=new Chain();
c.add(t.fun,["test",45]);
Out of the box, you can't. Furthermore, you can set property values of multiple objects with the same value, so the same function object might have multiple "parents".
I'm trying to write a simple Discord bot in TypeScript, using discord.js and clime.
I'm running into an issue where I'm trying to access an object property of a context object that I pass around, but it's always null. When I check the properties using either vscode's debugger or console.log, the object seems to have all of the properties that I would expect, except they're all nested one layer too deep.
export class DiscordCommandContext extends Context {
public message:Message;
public client:Client;
constructor (options:ContextOptions, message:Message, client:Client) {
super(options);
this.message = message;
this.client = client;
}
}
When I try accessing it the message property, it's always falsy (if block is skipped over).
if (context.message.guild) {
var settings = await repo.getRealmSettings(+context.message.guild.id);
if (key) {
embed.fields.push({name:key,value:settings[key]});
} else {
Object.keys(settings).forEach(property => {
embed.fields.push({name:property,value:settings[property]});
});
}
}
But in the console, I see this:
DiscordCommandContext appears to have nested "message" objects, one of the wrong type
I cannot access context.message.message, I get "Property 'message' does not exist on type 'Message'", which is as I would expect.
EDIT 1
My instantiation code looked like this:
var options:ContextOptions = {
commands: argArr,
cwd: ""
};
var context = new DiscordCommandContext(options, this.message, this.client );
Where argArr is a split string passed into the method and both this.message and this.client are populated in the constructor of the calling class (none are null)
I managed to get DiscordCommandContext to function properly by changing it to this:
export class DiscordCommandContext extends Context {
public message:Message;
public client:Client;
public realmSettings: RealmSettings;
constructor (options:ContextOptions, contextExtension:DiscordCommandContextValues) {
super(options);
this.message = contextExtension.message;
this.client = contextExtension.client;
this.realmSettings = contextExtension.realmSettings
}
}
export interface DiscordCommandContextValues {
message:Message;
client:Client;
realmSettings: RealmSettings;
}
And calling it like this:
var context = new DiscordCommandContext(options, {message:this.message, client:this.client, realmSettings: settings} );
I'm not sure if that's the right way or not... but it works.
I have an app.js with this code:
var addnote = (title,body) => { /* enter code here */ }
module.exports = {addnote};
Can I add another addnotes function with different parameters to that file?
Function overloading in JavaScript does not exist like in other programming languages such as C# and Java.
What you should be looking to do is pass an object as a parameter that has properties attached and filter them out there..
You could call different functions from your little 'mapping function' just implement the logic there if it isn't big (to keep the code clear).
function foo(parameters){
var title = parameters.title;
var body = parameters.body;
if(parameters.extraProperty){
// oh we have extraProperty passed in too, run a different function?
bar(title, body, parameters.extraProperty); // ??
}
}
foo({title: 'Title', body: 'Body', extraProperty: 'This is extra...'});
If this is your own custom module, you can use the concept of function overriding, where each child class can have its own way to handle something and also have a default way to do things.
class Parent {
constructor(name) {
this.name = name;
}
greet() {
console.log(`Hello ${this.name}`);
}
}
class Child1 extends Parent {
constructor(name) {
super(name);
}
greet() {
console.log(`Hey there ${this.name}. This is Child 1`);
}
}
class Child2 extends Parent {
constructor(name) {
super(name);
}
greet() {
console.log(`Hi there ${this.name}. This is Child 2`);
}
}
const o1 = new Child1('Foo')
const o2 = new Child2('Foo')
o1.greet();
o2.greet();
But if you are trying to override a function in an external module(You do not have access to that code, like a library), my suggestion is to create a wrapper and add functionality there.
I'm learning TypeScript and have the following class:
class DetailDriver {
public get driver() {
return super.getEntity();
}
public activate(): breeze.Promise {
var id = this.driver.id(); // this refers to (class) DetailDriver
return promise
.then(getCertificate)
.fail(somethingWrong);
function getCertificate() {
var id = this.driver.id(); // this refers to any
return ...
}
}
}
As you can see on the above code, the first call to this refers to my class DetailDriver. That's good. The second call to this (inside getCertificate) refers to any. That's not what I need. I need to refer to my class DetailDriver.
How to proceed?
Thanks.
Well,
According to section 4.9.2 of the TypeScript Language Specification you should use fat arrow syntax to preserve the scoping for this.
return promise
.then(() => return.this.id;)
.fail(somethingWrong);
Then the this keyword is properly determined to be a Driver.
For reference, you could also just do:
class SomeClass {
public someMethod() {
// Do something
}
public anotherMethod() {
var that = this; // Reference the class instance
function someFunction () {
that.someMethod();
}
}
}
You could refactor to something like this:
class DetailDriver {
public get driver() {
return super.getEntity();
}
public activate(): breeze.Promise {
var id = this.driver.id(); // this refers to (class) DetailDriver
return promise
.then(this.getCertificate.bind(this)) // <- important part
.fail(somethingWrong);
}
// new method function here
private getCertificate() {
var id = this.driver.id(); // this refers to any
return ...
}
}
Using the function keyword anywhere in your class will make any reference to this keyword refer to that function rather than the outer class. Generally, you want to avoid defining functions inside of classes, unless you use the "fat arrow" syntax. That would look like this:
class DetailDriver {
public get driver() {
return super.getEntity();
}
public activate(): breeze.Promise {
var id = this.driver.id(); // this refers to (class) DetailDriver
return promise
.then(() => { // <- important part
var id = this.driver.id(); // this refers to any
return ...
})
.fail(somethingWrong);
}
}