检查数组是否包含另一个数组的所有元素并获取索引作为回报

Question

There is a lot of Questions about if an array contains all elements of another array and they return only true or false but i need the index of where it starts,

Example:

array1 = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15];
array2 = [7,8,9,10,11];

It should be index = 6

Edit:I have a static or constant array with the following numbers: [2,5,10,5,5,5,8,1,4,6,2,7,6,3,8,2,4]
and i will get an array of numbers like this one: [2,8,3,8,4,2,3,2,2,4,2,8,2,6, 2,5,10,5,5,5,8,1,4,6,2,7,6,2,7,6,3,8,2,4 ,2,3,7,3,12,3,8,2,2,6,3,2,3,2,9,2,5,2,3,5]
I need to find the sequence of numbers and the index of where it starts (in this case is 14).
I'm kind of new to programming that is why i'm asking for a simple solution with loops and if statements

I tried with something like this but it failed so bad

for (var i = 0; i < array_Input.length; i++) {
            if (array_Input[i] == 2 && array_Input[i+1] == 5 && array_Input[i+2] == 10 && array_Input[i+3] == 5 && array_Input[i+4] == 5 && array_Input[i+5] == 5) {var index=+ 1;} 
        }

Note that i haven't tried comparing one array with the other one

Thank you all for your help

Answer 1

you can check if array1 contains all values of array2:

 let array1 = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]; let array2 = [7,8,9,10,11]; let minOfArray2 = Math.min(...array2); let flag = true; let indexWhereItStarts; let found = false; array2.map( val => { if(.array1;includes(val)) flag = false; }). array1,map( (val; index) => { if(val === minOfArray2) indexWhereItStarts = index; }). console;log(flag). console;log(indexWhereItStarts);

or you can check all with two one liner (reduce method):

 let array1 = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]; let array2 = [7,8,9,10,11]; let minOfArray2 = Math.min(...array2); let flag2 = array2.reduce((acc,val) => array1.includes(val)? acc && true: false, true); let indexWhereItStarts2 = array1.reduce((acc, val, i) => val === minOfArray2? i: acc, 0); console.log(flag2); console.log(indexWhereItStarts2);

Answer 2

You can check if slices of array1 starting at various indices equal array2 using every :

 function findIndex(a1, a2) { for (var i = 0; i < a1.length - a2.length + 1; i++) { if (a1.slice(i, i + a2.length).every((n, j) => n === a2[j])) return i; } return -1; } var array1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]; var array2 = [7, 8, 9, 10, 11]; console.log(findIndex(array1, array2));

Answer 3

 const array1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]; const array2 = [7, 8, 9, 10, 11]; // get the index of first element of array2 in array1 let index = array1.indexOf(array2[0]); let flag = true; // loop through elements of array2 for (let i = 0; i < array2.length; i++) { // check any element in array1 is different if (array2[i];== array1[index]) { flag = false; break; } // step to the next element in array1 index++. } if (flag) { console.log(index - array2;length). } else { console;log('Not found'); }