Comparing strings in TypeScript

After extensively studying string equality in JavaScript, I naturally assumed the same rules would apply in TypeScript. However, I am encountering a perplexing issue.

I have two identical strings that do not produce equal results when using the == and === operators.

Here is the code snippet:


this.cl_applied_filts.forEach (
    filt => {
        console.log (`[cl-filts]`);
        store.getState()._cl_filters.forEach(
            f => {
                // Code omitted for brevity
            }
        );
    });

The output in the Firefox console shows:


// Output omitted for brevity

The object declaration:


export class Filter
{
    checked : boolean = false;
    name : string = '';
}

Despite both strings being identical down to the byte level, they are producing non-equal results. Why is this happening?

store.string_eq is a custom function I created to compare strings byte by byte using the charCodeAt function in order to troubleshoot this issue efficiently. However, I am still puzzled by the outcome.

EDIT: After making adjustments based on feedback, there seems to be no difference in the comparison results.

Answer №1

After thorough investigation, I have identified the root cause of the issue and it goes beyond just strings.

The object labeled f is derived from a bencode object sourced from a GitHub library that escapes my memory.

The structure of the bencode object looks something like this:

{"checked":true,"name":{"type":"Buffer","data":[66,85,82,78,76,69,89]}

When trying to access the name property for display purposes, it gets converted into a string.

The filt (which is of type Filter) is fetched from a database where the name field is stored as a string.

However, when attempting to compare the name property between the two objects which should theoretically be the same since they are both considered as strings, they do not match up.

The actual problem lies in the fact that the bencode object's property isn't being properly converted into a string.

Therefore, even though the representation of

"name":{"type":"Buffer","data":[...]}
appears as a string when displayed and when converted into a String object, it fails to convert during comparison. This leads to a situation where we are essentially comparing:

{"type":"Buffer","data":[...]} == 'BURNLEY'

It seems that assigning one of these

"name":{"type"...
properties to a const string doesn't truly convert it into a string either, or perhaps it utilizes a different type of buffer. There must be an underlying factor causing them to not equate even when they appear identical and are classified as strings.

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