import convert = require("convert-source-map"); // tslint:disable:max-line-length var json = convert .fromComment('//@ sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoiZm9vLmpzIiwic291cmNlcyI6WyJjb25zb2xlLmxvZyhcImhpXCIpOyJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiQUFBQSIsInNvdXJjZVJvb3QiOiIvIn0=') .toJSON(); var modified = convert .fromComment('//@ sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoiZm9vLmpzIiwic291cmNlcyI6WyJjb25zb2xlLmxvZyhcImhpXCIpOyJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiQUFBQSIsInNvdXJjZVJvb3QiOiIvIn0=') .setProperty('sources', ['CONSOLE.LOG("HI");']) .toJSON(); console.log(json); console.log(modified);