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JavaScript JavaScript Functions Arrow Functions Testing for Number Arguments

Joseph Michelini
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Joseph Michelini
Python Development Techdegree Graduate 18,692 Points
Posted by Joseph Michelini
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Joseph Michelini
Python Development Techdegree Graduate 18,692 Points

Will I encounter a problem if a function parameter shares a name with a global variable?

In other words, does JS know if a function parameter is just a random placeholder word I made up, or if I'm passing it a variable declared somewhere else in the program? Does the syntax look exactly the same?

Thanks!

1 Answer

Steven Parker
Steven Parker
231,261 Points
Steven Parker
Steven Parker
231,261 Points

If a parameter has the same name as a global variable, it is said to "shadow" the global. This means that within the function, that name will refer to the parameter and not the global variable. This won't make any technical difference to your code as long as you don't need access to the global from within the function.

It could, however, lead to some confusion for other developers reading the code.

Joseph Michelini
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Joseph Michelini
Python Development Techdegree Graduate 18,692 Points
Joseph Michelini
.a{fill-rule:evenodd;}techdegree seal-36
Joseph Michelini
Python Development Techdegree Graduate 18,692 Points

Thanks Steven! Just to be clear, if a global variable has been declared, and a function has been declared with a parameter that shares a name with the global variable, when I call the function and pass an argument, does the function pass my argument or the value of the global variable?

Steven Parker
Steven Parker
231,261 Points
Steven Parker
Steven Parker
231,261 Points

The function receives your argument. That then "shadows" the global variable.