使用 Javascript 替换现有文件并推送到数组的顶部索引

Question

I need to push the current file that I find in the if statement if it is true, to the top item ... so I find it and transfer it to the top ....

  allProducts.forEach(
    (product) =>
      checkIfProductIsMoreThen200(product.price) && 
      allProducts.unshift(product)
  );

this is my try but no work...

he pushes me into the top index but leave me the old items ... and then it duplicates my current ones ... I don't want to duplicate the items ..

Answer 1

Have a look at Array.splice() , it should do the trick for you.

 const allProducts = [1, 2, 3]; console.log(`Before: ${allProducts}`) allProducts.forEach((product, index) => product == 3 && allProducts.unshift(allProducts.splice(index, 1)[0])); console.log(`After: ${allProducts}`)

Answer 2

Your code will indeed make the array longer while looping, which is a bad idea.

Instead you could use sort (for short code):

allProducts.sort((a, b) => checkIfProductIsMoreThen200(b.price) - 
                           checkIfProductIsMoreThen200(a.price));

For (very) long arrays, it will be more efficient to do this:

allProducts = allProducts.filter(a => checkIfProductIsMoreThen200(a.price)).concat(
    allProducts.filter(a => !checkIfProductIsMoreThen200(a.price))
);