Question

What dose this lines of js code means:

        ('selectionchange',function(sm, rs) {
            if (rs.length) {
                var detailPanel = Ext.getCmp('detailPanel');
                bookTpl.overwrite(detailPanel.body, rs[0].data);
            }
        })

this is a part of below link:
http://dev.sencha.com/deploy/ext-4.0.2a/examples/grid/binding-with-classes.js

---

Update:
I removed these lines and code runs without any diffrenece!
It’s a coding mistake
Thanks all

Answer 1

I’ll go out on a limb and call it an editing mistake. Here’s a little more context:

    initEvents: function() {
        // call the superclass's initEvents implementation
        this.callParent();

        // now add application specific events
        // notice we use the selectionmodel's rowselect event rather
        // than a click event from the grid to provide key navigation
        // as well as mouse navigation
        var bookGridSm = this.getComponent('gridPanel').getSelectionModel();
        ('selectionchange', function(sm, rs) {
        if (rs.length) {
            var detailPanel = Ext.getCmp('detailPanel');
            bookTpl.overwrite(detailPanel.body, rs[0].data);
        }
    })
        bookGridSm.on('selectionchange', this.onRowSelect, this);
    },

That is the only mention of bookTpl in the whole file. Someone copied what appears to be an event binding into their paste buffer and accidentally pasted it into this file or they pasted it in on purpose to check the syntax for the bookGridSm.on call and forgot to clean up after themselves.

Look for an errata list for the examples.