Local and global variables in Javascript - 00013

please ignore xPos and yPos values
codesample from khan academy

var lifeInches = 20; //

var calcInches = function(startAge, endAge, inchesPerYear) {
var totalInches = inchesPerYear * (endAge - startAge);
lifeInches += totalInches;
return totalInches;
};

fill(255, 0, 0);

text("From 0-8 years:", 10, 20);
text(calcInches(0, 8, 2.5), 10, 40);

text("From 8-16 years:", 10, 100);
text(calcInches(8, 16, 2), 10, 120);

text("Total grown over life:", 10, 168);
text(lifeInches, 10, 200);

output:
"From 0-8 years: 20"
"From 8-16 years: 16"
"Total grown over life: 56"

lifeInches -> global variable

totalInches -> local variable

calcInches -> local variable