The comparison of Booleans in Typescript sometimes produces inaccurate results

Question

The comparison of Booleans in Typescript sometimes produces inaccurate results

There is a strange issue I encountered in one of my classes involving a readonly boolean property. Whenever I try to check this property, the results are not as expected. Here is an example of the code:

// vorgang is a reference to the class, isEK is the property
let test = this.vorgang.isEK;
// Just for testing
let test2 = test ? true : false;
console.log(test + ' -> ' + test2);

As a result, I get the following output:

true -> true
false -> true

I am confused about what could be causing this unexpected behavior. Can you help me figure out what I am missing?

angular typescript

Answer 1

Answer №1

When dealing with strings, there is a possibility that your this.vorgang.isEK variable is a string.

If that is the case, you can update your code from let test2 = test ? true : false; to

let test4 = test3 == true ? true : false;

. Keep in mind that == only checks the value, not the data type.

Your revised snippet would look something like this -

// setting it as a string
let test = "false";
// Just for testing
let test2 = test == true ? true : false;
console.log(test + ' -> ' + test2);

Answer 2

When dealing with strings, there is a possibility that your this.vorgang.isEK variable is a string.

If that is the case, you can update your code from let test2 = test ? true : false; to

let test4 = test3 == true ? true : false;

. Keep in mind that == only checks the value, not the data type.

Your revised snippet would look something like this -

// setting it as a string
let test = "false";
// Just for testing
let test2 = test == true ? true : false;
console.log(test + ' -> ' + test2);

Answer 3

Answer №2

This property is a boolean value:

get isEK(): boolean {
  return this.art && this.art.netto;
}

The result is accurate but my comparison isn't functioning properly. It's frustrating me endlessly.

Answer 4

This property is a boolean value:

get isEK(): boolean {
  return this.art && this.art.netto;
}

The result is accurate but my comparison isn't functioning properly. It's frustrating me endlessly.

Answer 5

Answer №3

The only logical explanation is that during execution, the variable test contains the value 'false'.

let test = 'false';
let test2 = test ? true : false;
console.log(test + ' -> ' + test2); // false -> true

Try implementing this code for the isEK property:

get isEK(): boolean {
  return this.art && this.art.netto ? true : false;
}

You can also verify the type of a variable during execution with:

console.log('Type of test:', typeof test);

Answer 6

The only logical explanation is that during execution, the variable test contains the value 'false'.

let test = 'false';
let test2 = test ? true : false;
console.log(test + ' -> ' + test2); // false -> true

Try implementing this code for the isEK property:

get isEK(): boolean {
  return this.art && this.art.netto ? true : false;
}

You can also verify the type of a variable during execution with:

console.log('Type of test:', typeof test);

The comparison of Booleans in Typescript sometimes produces inaccurate results

Answer №1

Answer №2

Answer №3

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