JSFiddle - React, Tailwind, and code Playground
JavaScript
var newarray=new Array();
var test='[{"category":"test1","ID":"1","subcat":[{"completed":"4","uncompleted":"5"}]},{"category":"test2","ID":"2","subcat":[{"completed":"1","uncompleted":"5"}]}]';
var tags = JSON.parse(test);
for(i=0;i<tags.length;i++)
{
if(tags[i]['category']=='test1')
{
var subcat=tags[i]['subcat'];
for(j=0;j<subcat.length;j++)
{
newarray.push(subcat[j]['completed']);
newarray.push(subcat[j]['uncompleted']);
}
}
}
console.log(newarray);