Is my barcode valid?
JavaScript (ES6), 41 40 38 bytes
Saved 2 bytes thanks to @ETHProductions and 1 byte thanks to @Craig Ayre.
s=&gt;s.map(e=&gt;t+=e*(i^=2),t=i=1)|t%10==1

Takes input as a list of digits.
Determines the sum of all digits, including the checksum.
If the sum is a multiple of 10, then it's a valid barcode.
Test Cases


let f=

s=&gt;s.map(e=&gt;t+=e*(i^=2),t=i=1)|t%10==1

console.log(f([2,0,3,7,8,2,4,0]));
console.log(f([3,3,7,6,5,1,2,9]));
console.log(f([7,7,2,3,4,5,7,5]));
console.log(f([0,0,0,0,0,0,0,0]));

console.log(f([2,1,0,3,4,9,8,4]));
console.log(f([6,9,1,6,5,4,3,0]));
console.log(f([1,1,9,6,5,4,2,1]));
console.log(f([1,2,3,4,5,6,7,8]));