Why is the result of TypeScript delegates not equal?
someProperty: any;
someActionsWithItems(item: any) {
this.someProperty = "test";
}
// When using 'this', it works fine:
this.array.forEach(item => this.someActionsWithItems(item));
// However, if we use this approach, an error occurs because the context of 'this' isn't initialized (Cannot set property 'someProperty' of undefined):
this.array.forEach(this.someActionsWithItems);
What could be causing this discrepancy?
The key distinction lies in the arrow function. By utilizing the arrow function =>, it specifically connects this to the function.
In your particular scenario
this.array.forEach(item => this.someActionsWithItems(item));
is similar to
this.array.forEach(this.someActionsWithItems.bind(this));
You can explore more information on https://www.w3schools.com/js/js_function_closures.asp
as well as https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions
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