Setting an obj as counter with reduce

1

I feel this syntax is odd ally[fruit] = (tally[fruit] || 0) + 1. I’ assuming the following: I’m saying that (for each iteration) in the object tally the property fruit has a number as value and that number increases by one each time the same fruit is visited.
questions: || 0 is a way to initialize that value to zero (as a var-counter)?
wouldn’t be another (more readable) syntax for that purpose?

const fruitBasket = ['banana', 'orange', 'banana' ];
//A: in obj tally, the prop fruit is equal to a num (a counter)
//B: || 0 is an initialization of fruit-value to zero
const fruit_tally = arr => {
  const response = arr.reduce(function(tally, fruit){
    tally[fruit] = (tally[fruit] || 0) + 1 //A, B
    return tally;//returning obj
  }, {})//initializaing obj
  return response;
}

fruit_tally(fruitBasket);//--> { banana: 2, orange: 1 }
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2 
tally[fruit] = (tally[fruit] || 0) + 1

This is a shorthand version of

if (tally[fruit]) {
    tally[fruit] = tally[fruit] + 1;
} else {
    tally[fruit] = 0 + 1;
}
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