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Javascript – How to compare array elements one after another?

let a = [33, 15, 67, 203450, 212]

Above is the array that I am working with. I need to compare every previous element to the next one till the last element of the array. If the element is bigger than the one before it I add 2 into the "myNums". If the element is smaller than the one before it I add 1 into the "myNums". If the element equals the element before it I add 0 into the "myNums".

I made 3 functions to get me the sum of the digits I pushed into "myNums", but none of them works. So, how do I do this ?

Below are the functions I made to solve my problem.

function b(cmp) {
    for (let c = 0; c < cmp.length; c++) {
        let A = cmp[c]
        let B = cmp[c + 1]
        let myNums = []
        if (A < B) {
            myNums.push(1)
        }
        else if (A > B) {
            myNums.push(2)
        }
        else {
            myNums.push(0)
        }
        let sum = 0
        console.log(myNums)
        for (let d = 0; d < myNums.length; d++) {
            sum += myNums[d];
        }
        return sum
    }
}
let d = b(a)
console.log(d)
////////////////////////////////////////////////////////////////////////////////////
function b(cmp) {
    while ((c = 0) && (c < cmp.length)) {
        let A = cmp[c]
        let B = cmp[c + 1]
        let myNums = []
        while ((A < B) || (A > B) || A == B) {
            if (A < B) {
                myNums.push(1)
            }
            else if (A > B) {
                myNums.push(2)
            }
            else {
                myNums.push(0)
            }
        }
        let sum = 0
        for (let d = 0; d < myNums.length; d++) {
            sum += myNums[d];
        }
        return sum
    }
    c++
}
let d = b(a)
console.log(d)
//////////////////////////////////////////////////////////////////////////////////////
function b(cmp) {
    for (let c = 0; c < cmp.length; c++) {
        let A = cmp[c]
        let B = cmp[c + 1]
        let C = []
        let D = 0
        switch (B) {
            case (A < B):
                C.push(1)
            case (A > B):
                C.push(2)
            case (A == B):
                C.push(0)
        }
        for (let d = 0; d < C.length; d++) {
            D += C[d];
        }
        return C
    }
}
let e = b(a)
console.log(e)

They gave me either 0 or 1 or an empty array in the console.

Tags:

2

Answers


  1. 0

    this code will compare the array
    loop the element and check each one

    function compareElements(cmp) {
    let myNums = [];  

    for (let c = 0; c < cmp.length - 1; c++) {  // loop until the second last element
        let A = cmp[c];
        let B = cmp[c + 1];

        if (A < B) {
            myNums.push(2);  //bigger
        } else if (A > B) {
            myNums.push(1);  //smaller
        } else {
            myNums.push(0);  
        }
    }

    let sum = 0;
    for (let d = 0; d < myNums.length; d++) {
        sum += myNums[d];  // total
    }

    return sum;  
}

let a = [33, 15, 67, 203450, 212];
let result = compareElements(a);
console.log(result);
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  2. 0

    You could sliche the array and map the result by taking the sign of the delta with adjustments.

    const
    array = [33, 15, 67, 203450, 212],
    result = array
        .slice(1)
        .map((v, i) => (1 + Math.sign(v - array[i]) || 3) - 1);

console.log(result);

    A slightly better approach by taking an object for values.

    const
    values = { '-1': 2, 0: 0, 1: 1 },
    array = [33, 15, 67, 203450, 212],
    result = array
        .slice(1)
        .map((v, i) => values[Math.sign(v - array[i])]);

console.log(result);
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