How to display sequence of number and non sequence as abbrevated ?

For example Given numbers are 1,2,3,4,7,10, 12, 15,16,17,22 then the abbrevated result is 1-4,7,10,12,15-17,22. The solution i got is as following:

arr is the array of number which you want to pass and c = 0

ngOnInit(): void {

console.log('Entered array: ',this.arr);

var el = document.getElementById('firstvalue');

el.innerHTML = this.arr;

this.combo(this.arr);

}

combo(arr) {

this.result+= arr[0];

this.formethod(arr, this.c); //this.c=0;

}

formethod(arr, x) {

for(x;x

if(x != arr.length -1){

if(arr[x+1]-arr[x]==1)

{

let a=this.result.length;

if(!(this.result[a-1].includes('-')) && !this.result[a-1].includes(','))

{

this.result+='-';

}

else if(this.result[a-1].includes(',')){

if(arr[x+1]-arr[x]==1)

this.result+=arr[x]+'-';

else

this.result+=arr[x];

}

}

else {

if(x!=0)

this.result+=arr[x]+',';

else this.result+=',';

}

}

else {

this.result+=arr[x];

}

}

}

if you like the answer please support me.

Thank you