JSFiddle - React, Tailwind, and code Playground

JavaScript

var x = [
            {
                "Address1":"Mbezi Beach, Dar es salaam",
                 "searchstr":"Mbezi Beach, Dar es salaam"
            },
            {
                "Address1":"Regent Estate, Dar es salaam",
                "searchstr":"Regent Estate, Dar es salaam"
            },
            {
                "Address1":"Msasani Peninsula, Dar es salaam",
                "searchstr":"Msasani Peninsula, Dar es salaam"
            },
            {
                "Address1":"Msasani Peninsula, Dar es salaam",
                "searchstr":"no"
            }
        ];

 function getMatches(data,city){
		var matchArr = [];
		for (var i in data){		
				 var searchStr = data[i].searchstr;
                 var index = searchStr.indexOf(city);
                if(index!==-1) {
                    matchArr.push(data[i]);
                }
			}
			return matchArr;
		}

var arr = getMatches(x,'Dar es');
alert("arr: " + arr.length);