What is the best way to customize the string representation of a Boolean subclass in a function without causing any unintended consequences elsewhere in the

Question

What is the best way to customize the string representation of a Boolean subclass in a function without causing any unintended consequences elsewhere in the

Is there a way to wrap a boolean value in JavaScript so that comparisons remain intact and the resulting string is different from 'false' or 'true', all without changing the global boolean values?

function TestIt(bool){
    if(wrapper(bool) == true)
        return "it was: " + wrapper(bool)
    if(wrapper(bool) == false)
        return "it was: " + wrapper(bool)
    return "no dice"
}

For example:

var result;
result = TestIt(true);
// "it was: True"
result = TestIt(false);
// "it was: False"

I've been struggling to meet all of these conditions simultaneously with my attempts:

var initial = true;
var result1;
var result2;
(function(){
    result1 = wrapper(true);
    result2 = wrapper(true);
})()
// result1 == result2
// result1 == true
// result1.toString() != initial.toString()
// initial.toString() == true.toString()
// initial.toString() == (new Boolean(true)).toString()

Any help would be greatly appreciated.

I require this alternate string conversion for automatic duplication of server-generated strings in a different language, ensuring an exact match.

~~~~~~

Edit

~~~~~~

I forgot to mention the issue with the Boolean "valueOf" method being called instead of toString for string concatenation.

~~~~~~

Edit #2

~~~~~~

This also needs to work for false. Omitting it earlier caused some difficulties, especially when dealing with wrapper(false) == false.

~~~~~~

Edit Final

~~~~~~

The responses below showed that overriding the default behavior as I intended isn't possible when using string concatenation in Javascript. My plan now is to use an array solution and custom conversions during reassembly. It seems like JavaScript demands a unique approach to what should be a simple problem conceptually.

Command line code example:

function boolish(a){a=new Boolean(a);a.toString=function(){return this.valueOf()?"True":"False"};return a};

boolish(false) == false
boolish(true) == true
boolish(false) + " or " + boolish(true)
[boolish(false) , " or " , boolish(true)].join("~~~~~~~~")

javascript inheritance subclass subclassing prototypal-inheritance

Answer 1

Answer №1

I find it puzzling why you believe that this needs to happen automatically through toString(). If you have a simple boolean, you can use it in comparisons just like normal. However, if you wish to display custom text when concatenated, you can specify it at that moment. For instance, if you prefer "TRUE" and "FALSE" in all capital letters:

var myBool1 = false,
    myBool2 = true;

alert("The value of myBool1 is: " + (myBool1?"TRUE":"FALSE"));

Alternatively, you can create a small function:

function boolToString(val) {
   return val ? "True enough" : "That's a lie!";
}

alert("The value of myBool2 is: " + boolToString(myBool2));

UPDATE As per the relevant SO discussion (and responses): valueOf() vs. toString() in Javascript, it appears that your desired outcome cannot be achieved. When using the string concatenation + operator, it will always utilize valueOf rather than toString. It is indeed an odd behavior. One workaround is to concatenate the strings without using the + operator, although I understand if you prefer not to do so.

Answer 2

I find it puzzling why you believe that this needs to happen automatically through toString(). If you have a simple boolean, you can use it in comparisons just like normal. However, if you wish to display custom text when concatenated, you can specify it at that moment. For instance, if you prefer "TRUE" and "FALSE" in all capital letters:

var myBool1 = false,
    myBool2 = true;

alert("The value of myBool1 is: " + (myBool1?"TRUE":"FALSE"));

Alternatively, you can create a small function:

function boolToString(val) {
   return val ? "True enough" : "That's a lie!";
}

alert("The value of myBool2 is: " + boolToString(myBool2));

UPDATE As per the relevant SO discussion (and responses): valueOf() vs. toString() in Javascript, it appears that your desired outcome cannot be achieved. When using the string concatenation + operator, it will always utilize valueOf rather than toString. It is indeed an odd behavior. One workaround is to concatenate the strings without using the + operator, although I understand if you prefer not to do so.

Answer 3

Answer №2

Here is an example of how you can achieve this:

function customBoolean(value) {
  this.value = value;
}
customBoolean.prototype.toString = function() {
  return 'The boolean value is ' + (this.value? 'true' : 'false');
}

var myVar = new customBoolean(false);

console.log(myVar);  // 'The boolean value is false'

Answer 4

Here is an example of how you can achieve this:

function customBoolean(value) {
  this.value = value;
}
customBoolean.prototype.toString = function() {
  return 'The boolean value is ' + (this.value? 'true' : 'false');
}

var myVar = new customBoolean(false);

console.log(myVar);  // 'The boolean value is false'

What is the best way to customize the string representation of a Boolean subclass in a function without causing any unintended consequences elsewhere in the

Answer №1

Answer №2

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