Converting from string to number with the operator +

[Incrementis]

This copy paste from the wiki should explain the issue - Thank you for reading!

With the help of an example this will be now explained:

1. A text box in HTML is generated as follows

<input type = "text" id = "txt_one">

2. The value from the text box is fetched and converted as follows

+document.getElementById("bit").value;

There is an issue here which is the lack of knowledge from my side, how the converting property is working!
If you at any rate know some explanation or better a valid source, please post it under the section "issues" in this github project!Thank you very much!

[dotnetCarpenter]

document.getElementById("bit") get an Element that has an id of bit and not txt_one.

So the complete example should be:

<input type = "text" id = "txt_one">
<script>
  let value1 = +document.getElementById("txt_one").value;
</script>

Now what data type is value1? In this example, it can only be Number or String.

<input type = "text"> is represented in DOM as a HTMLInputElement (it inherit from Element), which has a .value property that returns a String value.

value: string: Returns / Sets the current value of the control.

The + operator, when used in front of a variable or expression, attempts to convert it's operand into a number. What is happening here, is explicit type coercion or type conversion. JavaScript always tried to convert data types into types that can be used where they are evaluated.

For example:

3 + "3" // 33 Number + String = String
3 + +"3" // 6 Number + Number(String) = Number
if (1) { console.log("true") } // 1 -> Boolean(1) -> true
if (0) { console.log("true") } // 0 -> Boolean(0) -> false

A simpler answer is available on stack overflow.

[Incrementis]

"document.getElementById("bit") get an Element that has an id of bit and not txt_one."

This example has been fixed in the wiki, but was posted wrongly here by copy and paste errors.
Thanks for the hint. It was actually:

1. A text box in HTML is generated as follows

<input type = "text" id = "bit" value = "2">

2. The value from the text box is fetched and converted as follows

+document.getElementById('bit').value;

Nevertheless your example seems more telling, so I changed it in the wiki to:
1. A text box in HTML is generated as follows

<input type="text" id="txt_one">

2. The value from the text box is fetched and converted as follows

<script>
  var myValue = +document.getElementById("txt_one").value;
</script>

Thank you for your valuable criticism, which helped me to understand the logic behind the operator +!
I put your answer in the wiki for reference :).

[dotnetCarpenter]

no problem :)