c4tugg
Last Updated: January 28, 2019
·
3.193K
· bashir

Find large javascript objects (crashing your app on iphone safari)

If you've ever wondered what the size of your objects and subelements are, here is a script to show you just that. I ran into a problem with using ember.js on iphone safari where memory is limited to 5 or 10MB and the page was crashing. I wanted to find out where we were using a lot of memory and the following code will show the problem areas.

function roughSizeOfObject( object) {

    var objectList = []
    var stack = [ object ];
    var bytes = 0;

    while ( stack.length ) {
        var value = stack.pop();

        if ( typeof value === 'boolean' ) {
            bytes += 4;
        }
        else if ( typeof value === 'string' ) {
            bytes += value.length * 2;
        }
        else if ( typeof value === 'number' ) {
            bytes += 8;
        }
        else if
        (
            typeof value === 'object'
            && objectList.indexOf( value ) === -1
        )
        {
            objectList.push( value );

            for( i in value ) {
                stack.push( value[ i ] );
            }
        }
    }
    return bytes;
} 

function printMemUsage(object, threshold) {
    var size;
    var at_least = (typeof threshold == 'undefined' ? 0 : threshold)

    for (element in object) {
        size = roughSizeOfObject(object[element]);
        if(size > at_least) {
            console.log(element + ":" + size);
        }
    }
}

you can call it as follows:

printMemUsage(MyApp, 1000)
activityFeedController:83012
ActivityListView:1110178
MoreActivityView:1110178
ActivityFeedView:1110178
ActivityStatsView:3432

3 Responses
Add your response

124

Clever, thanks for sharing!

over 1 year ago ·
356

I'm flattered.

over 1 year ago ·
363

@tomwrong looks like you had initially published the object sizing code. I want to make sure to give you the credit for it:
http://stackoverflow.com/questions/1248302/javascript-object-size/11900218#11900218

over 1 year ago ·