Get/ Resolve Term ID for Term Value in SharePoint.

getTermIdForTermValue.js

// Resolve Term ID for the Term Value 
        function getTermIdForTermValue(siteUri, listName, fieldName, termValue) {
            //Define
            var deferred = $q.defer()
            , termId;
            var clientContext = new SP.ClientContext(siteUrl);
            var list = clientContext.get_web().get_lists().getByTitle(listName);
            //Tx field
            var field = list.get_fields().getByInternalNameOrTitle(fieldName);
            var txField = clientContext.castTo(field, SP.Taxonomy.TaxonomyField);
            //load context
            clientContext.load(field);
            clientContext.load(txField);
            // //excute async of context
            clientContext.executeQueryAsync(
                //Success on Async
                Function.createDelegate(this
                        , function () {
                            //Getting term set of the field
                            var termSetId = txField.get_termSetId().toString();
                            var tSession = SP.Taxonomy.TaxonomySession.getTaxonomySession(clientContext);
                            var ts = tSession.getDefaultSiteCollectionTermStore();
                            var tset = ts.getTermSet(termSetId);
                            //Define term label to match
                            var lmi = new SP.Taxonomy.LabelMatchInformation(clientContext);
                            lmi.set_lcid(1033);
                            lmi.set_trimUnavailable(true);
                            lmi.set_termLabel(termValue);
                            var termMatches = tset.getTerms(lmi);
                            //context loading with taxanomy values
                            clientContext.load(tSession);
                            clientContext.load(ts);
                            clientContext.load(tset);
                            clientContext.load(termMatches);
                            clientContext.executeQueryAsync(
                                function () {
                                    if (termMatches && termMatches.get_count() > 0) {
                                        termId = termMatches.get_item(0).get_id().toString();
                                        console.log("Resolved Term Id for Term " + termValue, termId);
                                        deferred.resolve(termId);
                                    }
                                    else {
                                        console.log("No IDs to resolved for Term " + termValue);
                                        deferred.resolve(null);
                                    }
                                }
                                , function (sender, args) {
                                    console.log("Error on resolving term ID", args);
                                    deferred.reject(null);
                                });
                        }
                        , function (sender, args) {
                            console.log(args.get_message() + '\n' + args.get_stackTrace());
                        })
                //Failed on Async
                , Function.createDelegate(this, function (err) {
                    console.error(err.get_message());
                })
            );
            return deferred.promise;
        }