elfinder.min.js : How to get the data in the response

[medinib]

I created a new js function on the elfinder.min.js file :

elFinder.prototype.commands.importimage = function () {
        this.shortcuts = [{
            pattern: ""
        }], this.getstate = function (b) {
            var c = this.fm;
            return b = b || c.selected(), !this._disabled && b.length && a.map(b, function (a) {
                var b = c.file(a);
                return b && b.phash && !b.locked ? a : null
            }).length == b.length ? 0 : -1
        }, 
        this.exec = function (b) {
        	// Grise le bouton pour empecher les clics multiples
        	$('div[title="Insertion"]').addClass("ui-state-disabled");
            var c = this,
                d = this.fm,
                e = a.Deferred().fail(function (a) {
                    a && d.error(a)
                }),
                f = this.files(b),
                g = f.length,
                h = d.cwd().hash,
                i = !1,
                j = f[0].name;
            return this._disabled ? e.reject() : (a.each(f, function (a, b) {
                if (!b.phash) return !e.reject(["errImportJpeg", b.name, "errPerm"]);
                if (b.locked) return !e.reject(["errLocked", b.name]);
                b.hash == h && (i = d.root(b.hash))
            }), e.isRejected() || (f = this.hashes(b), d.confirm({
            	title: d.i18n(c.title),
                text: d.i18n(["confirmInsert", j, "confirm"]),
                accept: {
                    label: "btnYes",
                    callback: function () {
                        d.lockfiles({
                            files: f
                        }), d.request({
                            data: {
                                cmd: "importimage ",
                                targets: f,
                                current: h
                            },
                            notify: {
                                type: "mkfile",
                                cnt: g
                            },
                            preventFail: !0
                        }).fail(function (a) {
                        	if(a == "ERREUR_CONCURRENCE") {
                        		alert("error");
                            	window.location.href = document.getElementById('navAccueil').href;
                        	} else {
                        		e.reject(a);
                        	}
                        }).done(function (a) {
                        	alert(a);
                        	elFinderDone(a, 'importimage ');
                        }).always(function () {
                            d.unlockfiles({
                                files: f
                            })
                        })
                    }
                },
                cancel: {
                    label: "btnNo",
                    callback: function () {
                        e.reject()
                    }
                }
            })), e)
        }
    }

I need to get the data in the response to display them in a popup. The following code :

.done(function (a) {
                        	alert(a);
                        	elFinderDone(a, 'importimage ');
                        })

returns the following error " Syntax Error: Invalid character" when parsing the "a" argument of "elFinderDone(a, 'importimage ');" :
var obj = JSON.parse(a);

So my question is : how to get the json data correctly ?