Converting

A lot of data types are converted automatically.
The window.alert function will convert any value passed in to a string.


String Conversion

You can use the String function to explicitly convert a value to a string

let var1 = true; 
var1 = String(var1);
// var1 contains the value "true"

Use parseInt and parseFloat
These convert numerical strings to numbers
parseFloat is for floating point numbers, which are numbers with decimal points


Use toString
Convert numbers to numerical strings

console.log( (100).toString() );   //  "100" 

Number Conversion

You can use the Number function to explicitly convert a value to a number

let var2 = '50';  
var2 = Number(var2);
// var2 contains the value 50

let var3 = Number('this is some text'); 
// var3 contains the value NaN

Most mathematical operations convert values to numbers although the '+' operator has one exception to this rule.
If one of the values is a string then the other value is converted to a string.

let var4 = 1 + '2';  
// var4 contains '12'
let var5 = '1' + 2
// var5 contains '12'

Converting string to a number

parseFloat(text) 
parseInt(text)

something = Number(localStorage.getItem("fieldname"); 

Boolean Conversion

You can use the Boolean function to explicitly convert a value to a boolean.
The following values are converted to false:
"empty", 0, "" (empty string), undefined, NaN
Everything else becomes true



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