Styjun

I am new to ionic 3 and want to know about the code please help me out guy's.
I want to select any item and it's value get's changed subtotal may reflect's to it output.

cart.ts

private _values1 = [" 1 ", "2", " 3 "," 4 "," 5 "," 6 "];

 firstDropDownChanged(_values1: any) 
 
 this.currentPrice = (parseInt(this.product.subtotal) * this._values1);
 console.log(this.currentPrice);
 this.product.subtotal =this.currentPrice;
 console.log(this.product._values1);
 

cart.html

 <span style="font-size: 14px !important;">Qty:</span> 
 <select class="sel" (change)="firstDropDownChanged()">
 <option *ngFor='let v of _values1'> v </option>
 </select>

You can use 2-way data-binding using [(ngModel)] as

<select class="sel" (change)="firstDropDownChanged()" [(ngModel)]="selectedValue">
 <option *ngFor='let v of _values1' [ngValue]="v"> v </option>
 </select>

So, on every change of option, the current value of selected option will be in selectedValue variable. Use in .ts file as

firstDropDownChanged() 
 this.currentPrice = this.product.subtotal * this.selectedValue;
 console.log(this.currentPrice);
 this.product.subtotal =this.currentPrice;
 

Stackblitz Demo using ngModel

Try this in TS

 this.currentPrice = this._values1.map((value: number) => 
 return parseInt(this.product.subtotal) * value 
 );

And in HTML add below in Select

(change)="firstDropDownChanged($event.target.value)"

you can try like this i hope it helps you out

TS

currentPrice: number = 0;
private _values1 = [" 1 ", "2", " 3 "," 4 "," 5 "," 6 "];

firstDropDownChanged(data: any) 

 this.currentPrice = +this.product.subtotal * +data.target.value;
 console.log(this.currentPrice);
 this.product.subtotal = this.currentPrice;

HTML

 <select class="sel" (change)="firstDropDownChanged($event)">
 <option *ngFor='let v of _values1'> v </option>
 </select>

let me know if it is working or not

Here you need to pass the selected value using $event.target.value in your firstDropDownChanged() method like below

component.ts

private _values1 = [1, 2,3, 4, 5, 6];
 currentPrice = 10;
 product = 
 subtotal : 10,
 _values1 : 1
 
 firstDropDownChanged(_values1: any) 
 this.currentPrice = this.product.subtotal * _values1;
 console.log(this.currentPrice);
 this.product.subtotal =this.currentPrice;
 console.log(this.product._values1);

 

component.html

 <select class="sel" (change)="firstDropDownChanged($event.target.value)">
 <option *ngFor='let v of _values1'> v </option>
 </select>

Here is stackblitz link

Hope this will help!