当在 Javascript 中重复时，如何循环创建具有两个元素的另一个数组？

Question

I want to create a two-dimensional array from another existent array, which is scraped from a website through document.querySelectorAll(). I want to add from two to two depending on the elements of the array. Let me show you an example to make me more understandable.

myArray = ["price $33", "extra $2", "price $54", "price $20", "extra $3.5", "price $25", "extra $2", "price $31"]

In theory, every two elements are paired (the strings with "extra" are related with the strings with "price"). However, as you can see there are prices that do not have extras . Every extra comes with the previous price. I want to add the price and its extra together as well as the price alone. Like this:

new array = [["price $33", "extra $2"], ["price $54"], ["price $20", "extra $3.5"], ["price $25", "extra $2"], ["price $31"]]

Thank you very much!

Answer 1

You could reduce the array and check if the string starts with extra , then push the the last array of add a new array with the string.

 var array = ["price $33", "extra $2", "price $54", "price $20", "extra $3.5", "price $25", "extra $2", "price $31"], result = array.reduce((r, s) => { if (s.startsWith('extra')) r[r.length - 1].push(s); else r.push([s]); return r; }, []); console.log(result);

 .as-console-wrapper { max-height: 100%;important: top; 0; }

Answer 2

You could do this with clever use of reduce including a flag to say whether to skip the next element. Something like below:

 var myArray = ["price $33", "extra $2", "price $54", "price $20", "extra $3.5", "price $25", "extra $2", "price $31"]; var newArray = myArray.reduce( (agg, item, index, arr) => { if(agg.skipNext) { agg.skipNext = false; return agg; } if(index < arr.length-1 && arr[index+1].startsWith("extra")) { agg.skipNext = true; agg.push([item,arr[index+1]]); } else agg.push([item]); return agg; },[]); console.log(newArray);