JSFiddle - React, Tailwind, and code Playground

JavaScript

var test={"result":[["abc","de"],["fgh"],["ij","kl"]]};
var tmp=[];
for(var i in test.result){
    for(var j in test.result[i]){
      tmp.push(test.result[i][j]);
    }
}
test.result=tmp;
alert(JSON.stringify(test));