Search for a subarray in an array in JavaScript

Question

I have an array of Objects:

arrObj : [{ id: 0, text: 'At', start: '15.000' },
      { id: 1, text: 'the', start: '15.492'},
      { id: 2, text: 'left', start: '15.984'},
      { id: 3, text: 'we', start: '16.476' },
      { id: 4, text: 'can', start: '16.967'},
      { id: 5, text: 'see...', start: '17.459' },
      { id: 6, text: 'At', start: '18.166'},
      { id: 7, text: 'the', start: '18.440' }]

I have to search for an array and return the start and end word ids. For example in this case:

["At", "the"]

I have to return [(0,1),(6,7)] I am currently using a for each loop to iterate over the arrObj and see if the words match. I also tried indexOf by joining the objects texts but it returns the char index not array index.

But this does not seem efficient. How can i efficiently search for something like this?

Answer 1

You could use reduce to get the start and end positions in an array:

 let arrObj = [{ id: 0, text: 'At', start: '15.000' }, { id: 1, text: 'the', start: '15.492'}, { id: 2, text: 'left', start: '15.984'}, { id: 3, text: 'we', start: '16.476' }, { id: 4, text: 'can', start: '16.967'}, { id: 5, text: 'see...', start: '17.459' }, { id: 6, text: 'At', start: '18.166'}, { id: 7, text: 'the', start: '18.440' }]; let arr = ["At", "the"]; let res = arrObj.reduce((a, b, i) => { let index = arr.indexOf(b.text); if (index === 0) { a.push(i); } else if (index === 1) { a.push([a.pop()].concat(i)); } return a; }, []); console.log(res); 

Note that this will only work if the array with the searchterms holds 2 entries.

If you need more than two searchterms in the array, this will work:

 let arrObj = [{ id: 0, text: 'At', start: '15.000' }, { id: 1, text: 'the', start: '15.492'}, { id: 2, text: 'left', start: '15.984'}, { id: 3, text: 'we', start: '16.476' }, { id: 4, text: 'can', start: '16.967'}, { id: 5, text: 'see...', start: '17.459' }, { id: 6, text: 'At', start: '18.166'}, { id: 7, text: 'the', start: '18.440' }] let arr = ["At", "the", "left"]; let res = arrObj.reduce((a,b,i) => { let index = arr.indexOf(b.text); if (index > -1) { if (index % arr.length === 0) { a.push(i); } else { let tmp = a.pop(); a.push(tmp instanceof Array ? tmp.concat(i) : [tmp].concat(i)); } } return a; }, []); console.log(res); 

Answer 2

A solution for any length of a search array. It stores the index of the search array and increments with a match.

It adds only an array with the indices, if the indices for all items of the search array are found.

 var array = [{ id: 0, text: 'At', start: '15.000' }, { id: 1, text: 'the', start: '15.492' }, { id: 2, text: 'left', start: '15.984' }, { id: 3, text: 'we', start: '16.476' }, { id: 4, text: 'can', start: '16.967' }, { id: 5, text: 'see...', start: '17.459' }, { id: 6, text: 'At', start: '18.166' }, { id: 7, text: 'the', start: '18.440' }], search = ["At", "the"], result = array.reduce(function (i, t) { return function (r, a, j) { if (search[i] === a.text) { t.push(j); i++; if (i === search.length) { r.push(t); t = []; i = 0; }; } return r; }; }(0, []), []); console.log(result); 

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