Beginners question on numeric conversion


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Code:
let str = "123"; alert(typeof str); //
string let num = Number(str); //
becomes a number 123 alert(typeof num); // number


kindly explain

Code:
let num = Number(str); // becomes a number 123

i dont follow

thanks!!
 
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Double or single quotes make the expression between them a string, Number() turns /* in case it consists of digits, but is a string */ the expression between it's braces into a number. Nothing but a simple magic <wink>
 
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thanks!

another question, please

The unary plus or, in other words, the plus operator + applied to a single value, doesn’t do anything to numbers. But if the operand is not a number, the unary plus converts it into a number.

For example:

Code:
// No effect on numbers
let x = 1;
alert( +x ); // 1

let y = -2;
alert( +y ); // -2

// Converts non-numbers
alert( +true ); // 1
alert( +"" );   // 0

please help with the whole concept
 
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+ isn't convert anything to a number at all.

Code:
var a = "1";
var b=2;
var c= a + b;
alert(c);

//WILL ALERT 12 (1+2)
//BUT

var c=parseFloat(a)+b;
alert(c);
//WILL ALERT 3;
 
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+ isn't convert anything to a number at all.

Code:
var a = "1";
var b=2;
var c= a + b;
alert(c);

//WILL ALERT 12 (1+2)
//BUT

var c=parseFloat(a)+b;
alert(c);
//WILL ALERT 3;

if you put + to the proper place some strings will suddenly turn to numbers:

JavaScript:
const a = "1";
const b = 2;
const c = + a + b;
alert(c);
 
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Yes my bad. I've tried it by myself. Anyway. That's a really bad habit of coding which nobody should ever get used to. NEVER MIX TYPES.

But my claim is still right. An Math operator isn't convert any type to another type. In that particular example it worked.
 

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