data change doesn't reflect in vue application - vue.js

Question

In my Vue application I am trying to create a simple table with changeable column sequence. In the data structure I keep all column data with its thead. I use compute to calculate rows from column data using matrix transposion. However any change I do to dynamicTable.columns doesn't reflect in the view.
function transpose(a)
{
return a[0].map(function (_, c) { return a.map(function (r) { return r[c]; }); });
// or in more modern dialect
// return a[0].map((_, c) => a.map(r => r[c]));
}
var tData = {
columns:[
{thead:'isbn',
tdata:[1,2]},
{thead:'name',
tdata:['rose','flower']},
{thead:'price',
tdata:['10','15']},
{thead:'author',
tdata:['john','jane']},
{thead:'page count',
tdata:['396','149']},
{thead:'print date',
tdata:['2001', '1996']}
]
}
var dynamicTable = new Vue({
el: '#dynamicTable',
data: tData,
computed:{
rows: function(){
arr = [];
this.columns.forEach(function(element){
arr.push(element.tdata);
});
return transpose(arr)
}
}
})
For example I want to change the order of isbn column with price,
a=dynamicTable.columns[0]
b=dynamicTable.columns[2]
dynamicTable.columns[0]=b
dynamicTable.columns[1]=a
data changes but changes are not reflected. What is the problem here?

Answer 1

As mentioned in the documentation, this is a JavaScript limitation. Direct changes to an array are not detected by Vue.
One workaround for this, is to use Vue.set(), as instructed in the link.