在js数组中查找顺序值

Question

What's wrong with this code?

I'm experimenting with a simple card game to see if one has a straight.

The logic is to just check if the next value in the array is the current value + 1

 let arr = [ [ 'd', 13 ], [ 'f', 12 ], [ 'z', 11 ], [ 'd', 10 ], [ 'd', 9 ] ]; arr = arr.sort((a,b) => a[1] - b[1]); const isSeq = arr => { for (let i = 0; i < arr.length - 1; i++) { console.log(arr[i][1]+1, arr[i+1][1]) if (arr[i][1]+1 !== arr[i+1][1]) { return false; } else { return true; } } } isSeq(arr);

Answer 1

You need to remove the else part, because this would exit the function even if true in the first iteration.

 let arr = [[ 'd', 13 ], [ 'f', 12 ], [ 'z', 11 ], [ 'd', 10 ], [ 'd', 9 ]]; arr = arr.sort((a, b) => a[1] - b[1]); const isSeq = arr => { for (let i = 0; i < arr.length - 1; i++) { console.log(arr[i][1] + 1, arr[i + 1][1]); if (arr[i][1] + 1 !== arr[i + 1][1]) { return false; } } return true; }; console.log(isSeq(arr));

Answer 2

You're quick returning after the first check, one way or the other.

if (arr[i][1]+1 !== arr[i+1][1]) {
    return false;
} else {
    return true;
}

You should return after all the checks have been done:

for (let i = 0; i < arr.length - 1; i++) {
    console.log(arr[i][1]+1, arr[i+1][1])
    if (arr[i][1]+1 !== arr[i+1][1]) {
        return false;
    }
  }
  return true;

Answer 3

You can also do this with Array#every() :

 let arr = [ ['d', 13], ['f', 12], ['z', 11], ['d', 10], ['d', 9] ]; arr = arr.sort((a, b) => a[1] - b[1]); function isSeq(data) { return data.every((num, i) => (i === data.length - 1) || (num[1] === (data[i + 1][1] - 1))); } console.log(isSeq(arr));

This first checks if the index is the last, and if not makes sure that the current element is equal to array[i+1]-1

Answer 4

Instead if else with return , you can use break :

Take the first value as the current and iterate the remainder of the input. Compare each entry to the current. If the sequence is broken, break from the loop. Before moving to the next entry, set this as one as the new current.

 let arr = [ [ 'd', 13 ], [ 'f', 12 ], [ 'z', 11 ], [ 'd', 10 ], [ 'd', 9 ] ]; arr = arr.sort((a,b) => a[1] - b[1]); const isSeq = arr => { let isStraight = true let current = arr[0][1] for (let i = 1; i < arr.length; i++) { if (arr[i][1] !== current + 1) { isStraight = false break } current = arr[i][1] } return isStraight } console.log(isSeq(arr))