Is JavaScript capable of producing different results with the same input?

Question

Is JavaScript capable of producing different results with the same input?

I am currently revising one of my scripts and have come across a perplexing issue. The variable command is an input, and I conducted the following test with identical regular expressions:

var parts = command.match(/([^\s"]+(?=\s*|$))|(".+?")/g);
console.log(command === "view -10 10 -10 10");
console.log(parts);
console.log(String("view -10 10 -10 10").match(/([^\s"]+(?=\s*|$))|(".+?")/g));

When I check the console, it displays:

true
[]
["view", "-10", "10", "-10", "10"]

This situation has left me completely baffled. Why is the separation of command not the same, despite being identical to my test string and using ===?

javascript variables

Answer 1

Answer №1

Response from Original Poster

Here is the resolution to the entire issue: The program's basic structure looked like this:

while (<condition>) {
    var command = getNextCommand();

    var parts = command.match(/([^\s"]+(?=\s*|$))|(".+?")/g);
    processParts(parts);
}

The function processParts() was responsible for manipulating the argument:

function processParts(parts) {
    var foo = parts.shift();
    doSomethingElse(foo);
}

This resulted in the shrinking of parts in the main routine, and in my code, processParts actually removed all elements using the shift method, leading to console.log(parts) displaying an empty array due to delayed logging (as pointed out by dystroy).

In addition, there was an error in my processParts() function that I failed to notice, so I mistakenly attributed the empty parts to it. Once I corrected this mistake, the aforementioned code began functioning properly again since I no longer required parts and could accept its reduced size. It's advisable to be cautious about such occurrences, as JavaScript can behave unexpectedly at times.

Answer 2

Response from Original Poster

Here is the resolution to the entire issue: The program's basic structure looked like this:

while (<condition>) {
    var command = getNextCommand();

    var parts = command.match(/([^\s"]+(?=\s*|$))|(".+?")/g);
    processParts(parts);
}

The function processParts() was responsible for manipulating the argument:

function processParts(parts) {
    var foo = parts.shift();
    doSomethingElse(foo);
}

This resulted in the shrinking of parts in the main routine, and in my code, processParts actually removed all elements using the shift method, leading to console.log(parts) displaying an empty array due to delayed logging (as pointed out by dystroy).

In addition, there was an error in my processParts() function that I failed to notice, so I mistakenly attributed the empty parts to it. Once I corrected this mistake, the aforementioned code began functioning properly again since I no longer required parts and could accept its reduced size. It's advisable to be cautious about such occurrences, as JavaScript can behave unexpectedly at times.

Is JavaScript capable of producing different results with the same input?

Answer №1

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