javascript - Lowercase of object value in array with underscore js - Stack Overflow

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Let's say I have this JSON data in a data variable

[{"id":"1","module_id":"1","title":"Test",
  "start_date":"2012-11-12" "end_date":"2012-11-18"},
 {"id":"8","module_id":"1","title":"This is OK",
  "start_date":"2013-01-14","end_date":"2013-01-31"}]

How do I use underscore.js to get following result?

[{"id":"1","module_id":"1","title":"test",
  "start_date":"2012-11-12","end_date":"2012-11-18"},
 {"id":"8","module_id":"1","title":"this is ok",
  "start_date":"2013-01-14","end_date":"2013-01-31"}]

Can I do this with invoke ?

Let's say I have this JSON data in a data variable

[{"id":"1","module_id":"1","title":"Test",
  "start_date":"2012-11-12" "end_date":"2012-11-18"},
 {"id":"8","module_id":"1","title":"This is OK",
  "start_date":"2013-01-14","end_date":"2013-01-31"}]

How do I use underscore.js to get following result?

[{"id":"1","module_id":"1","title":"test",
  "start_date":"2012-11-12","end_date":"2012-11-18"},
 {"id":"8","module_id":"1","title":"this is ok",
  "start_date":"2013-01-14","end_date":"2013-01-31"}]

Can I do this with invoke ?

• javascript
• underscore.js

Share Improve this question Follow edited Mar 28, 2013 at 0:58 pb2q 59.6k1919 gold badges150150 silver badges152152 bronze badges asked Mar 19, 2013 at 21:24 duivvvduivvv 1111 gold badge11 silver badge55 bronze badges 5

• 1 Is it really JSON (i.e., a string), or is it an object? If it's a string, you can just .toLowerCase() it. – bfavaretto Commented Mar 19, 2013 at 21:27
• I know what toLowerCase() is :) .. It's JSON – duivvv Commented Mar 19, 2013 at 22:02
• 2 That's my point. JSON is always a string representation of an object. If it's not a string, it's not JSON. So, if it's an object, maybe you could use var transformed = JSON.parse(JSON.stringify(obj).toLowerCase()). – bfavaretto Commented Mar 19, 2013 at 22:04
• ok but I only want a certain property for all objects in the array to lowercase. Not the plete string. – duivvv Commented Mar 19, 2013 at 22:08
• In your example, you have only one field with alphabetic characters in it. Are there others in the real data? If not, bfavaretto's solution is a very simple one. – Scott Sauyet Commented Dec 2, 2014 at 15:46

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4 Answers 4

Sorted by: Reset to default 6

You can do this easily with Lo Dash's _.mapValues function:

_.mapValues(objs, function(s){
  return _.isString(s) ? s.toLowerCase() : s;
});

If you're already dealing with an object (or parsed JSON), you can loop and create a new one:

var objs = [{"id":"1","module_id":"1","title":"Test", "start_date":"2012-11-12", "end_date":"2012-11-18"},{"id":"8","module_id":"1","title":"This is OK", "start_date":"2013-01-14","end_date":"2013-01-31"}];

var out = [];
for(var i=0; i<objs.length; i++) {
    var outObj = {}
    for(var prop in objs[i]) {
        var val = objs[i][prop];
        if(prop === 'title') {
            val = val.toLowerCase();  
        }
        outObj[prop] = val;
    }
    out.push(outObj);
}
console.log(out);

http://jsfiddle/uY36J/

If you have array of objects:

for(var i = 0; i < array.length; i++) {
   for (var prop in array[i])
       // condition here
       array[i][prop] = array[i][prop].toLowerCase();
}

console.log(array)

Same with underscore (I don't think it's much shorter - you still need two loops here. More readable - maybe, but not shorter)

_.each(array, function(obj) {
    _.each(obj, function(value, key) { 
        // condition here        
        obj[key] = value.toLowerCase();
    });
});

You can separate the object in two arrays, one with the keys and the other with the values, then use _.map to lowercase the strings.

var objs = [{"id":"1","module_id":"1","title":"Test", "start_date":"2012-11-12", "end_date":"2012-11-18"},{"id":"8","module_id":"1","title":"This is OK", "start_date":"2013-01-14","end_date":"2013-01-31"}];

 _.map(objs,function(element) {
     return  _.object(_.keys(element), _.values(element).map(function(value) { 
         return _.isString(value)? value.toLowerCase():value; 
     }));
 });

you see, I'm checking if it's a string we're dealing with, to avoid calling toLowerCase on other types.

Lowercasing both keys and values is trivial as well

 _.map(objs,function(element) {
     return  _.object(
         _.keys(element).map(function(key) { 
             return _.isString(key)? key.toLowerCase():key; 
         }),
         _.values(element).map(function(value) { 
             return _.isString(value)? value.toLowerCase():value; 
         })
     );
 });

Caveat: this will not operate on nested objects. ¯\_(ツ)_/¯

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