尽管函数返回false，但Array.filter（）不会过滤元素

Question

I'm trying to use the filter function to remove an element from an array. This is in Typescript/Angular6 but I think this snippet applies to JS in general.

Below code does not seem to filter out the element I want despite the filter function returning false for that element. At least I think it returns false as the comparison evaluates to false (see output).

The verbose manual function with Array.splice() does do its job. What am I not seeing?

  public deleteAltChar() {
    console.log(this.char.altchars);
    this.charService.deleteAltChar(this.altChar, this.char)
      .subscribe(data => {
        // THIS DOES NOT WORK
        this.char.altchars.filter(ac => {
            console.log(ac);
            console.log(this.altChar);
            console.log(this.altChar != ac);
            return ac != this.altChar;
        });
        console.log(this.char.altchars);
        // THIS DOES WORK
        // this.char.altchars.forEach(ac => {
        //  if (ac == this.altChar) {
        //      this.char.altchars.splice(this.char.altchars.indexOf(ac), 1);
        //  }
        // });
      });
  }

output from first part:

Array[0: Object { id: 37 }]
Object { id: 37 }
Object { id: 37 }
false
Array[0: Object { id: 37 }]

Answer 1

Array.filter returns a new array with the filtered values, it doesn't change the instance it's invoked on, check the documentation

So you would wanna do something like that

this.char.altchars = this.char.altchars.filter(ac => ac != this.altChar);

Answer 2

Array.filter returns a new array, thus you need assign result of filter to some variable.

this.char.altchars = this.char.altchars.filter(ac => {
     console.log(ac);
     console.log(this.altChar);
     console.log(this.altChar != ac);
     return ac != this.altChar;
});