How to compare a variable against another from an array of objects?

Question

I'm trying to compare event.feature.getProperty('township') against timeline.townshipname from my timeline array in my if. Checking for one right now with [0] is fine, but I have a whole column I want to check against. What's the best way to do this?

    //Load Timelines
    var timeline = [];
    jQuery.getJSON(timelines, function(data) {
        var entry = data.feed.entry;
        jQuery(entry).each(function(){
            var townshipname = this.gsx$township.$t;
            var timelinename = this.gsx$timeline.$t;
            var combined = {townshipname, timelinename};
            timeline.push(combined);
        });
    }); 
    // Output from timeline looks like
    // 0: {townshipname: "West Quincy", timelinename: "Ready for drops"}
    // 1: {townshipname: "Woodgate", timelinename: "Ready"}

    //Add infowindow to identify townships
    township_layer.addListener('click', function(event) {
        if (event.feature.getProperty('township') == timeline[0].townshipname){         
            var timepush = timeline[0].timelinename
        } else {
            var timepush = 'No Timeline Entered'
        }

Loop through the array until you find a match. Break if you find one — charlietfl
– charlietfl, Commented Apr 8, 2019 at 21:23
Hello, I see on the out is says 'townshipname', but you're trying to find the property of 'township'. Is it 'townshipname' or 'township"? — Mark Hill
– Mark Hill, Commented Apr 8, 2019 at 21:24
I'm comparing against one that is township (event.feature.geProperty('township') and the other that is townshipname (timeline.townshipname). Two different sources with similar names. — jerime
– jerime, Commented Apr 8, 2019 at 21:27

Terry · Accepted Answer · 2019-04-08 21:38:03Z

You can create an array of township names from the timeline array of objects, so that you can compare if a specific township is found in your timeline.

This can be done by:

Using Array.prototype.map() to iterate through your timeline array of objects and return a list of all townshipname
Check if a given township is present in your array by using Array.prototype.indexOf()

Example code is as follow:

// Generate an array of townships extract from timeline
var townships = timeline.map(function(item) {
  return item.townshipname;
});

// Attempt to search a given township in your generated array
var townshipIndex = townships.indexOf(event.feature.getProperty('township'));

if (townshipIndex !== -1) {         
    var timepush = timeline[townshipIndex].timelinename;
} else {
    var timepush = 'No Timeline Entered';
}

Alternatively, you can use a for...of loop and break out of it once a match is found. We assume that no timeline is entered as the "ground state", and then we can update that once a match is found:

var timepush = 'No Timeline Entered';
for (var item of timeline) {
  if (item.townshipname === event.feature.getProperty('township')) {
    timepush = item.timelinename;
    break;
  }
}

If you really need IE support, then we can use the classic for loop:

var timepush = 'No Timeline Entered';
for (var i = 0; i < timeline.length; i++) {
  if (timeline[i].townshipname === event.feature.getProperty('township')) {
    timepush = timeline[i].timelinename;
    break;
  }
}

Mark Hill · Accepted Answer · 2019-04-08 21:26:51Z

0

So there are a couple of different ways you could this, if you have an indexed array of objects the fastest way would be:

for(var i = 0; i < timeline.length; i++){
    if(event.feature.getProperty('township') == timeline[i].townshipname){
        var timepush = timeline[i].timelinename;
    }
}

I can come up with another example shortly.

answered Apr 8, 2019 at 21:26

Mark Hill

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