var is globally scoped and hoisted, which can lead to unintended side effects. let is block-scoped and can never be redeclared within that scope – much harder to break, but need to be careful about passing it to where it's needed and aware that it is still hoisted, albeit with no value (not even null). const works similarly to let, but you cannot update the value (though you can update internal values).
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- const, let, var, variables, JavaScript, scope
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- <!DOCTYPE html> <html> <head> <title></title> </head> <body> <p>var is globally scoped and hoisted, which can lead to unintended side effects. let is block-scoped and can never be redeclared within that scope – much harder to break, but need to be careful about …</p> </body> </html>
- Murray Champernowne
