Fast JSON string escaping in JS.
It is faster to escape small JSON strings manually than using native
JSON.stringify().
The main focus is a very fast check for strings that do not need any escaping while also improving escaping itself or at least not to go below JSON.stringify.
Running the benchmarks (npm run benchmark) show the benefits:
node ./benchmark
JSON short non escaped x 2,884,878 ops/sec ±2.25% (95 runs sampled)
this short non escaped x 13,082,026 ops/sec ±1.47% (93 runs sampled)
JSON short full escape 1 x 2,768,607 ops/sec ±1.85% (86 runs sampled)
this short full escape 1 x 3,232,099 ops/sec ±2.39% (90 runs sampled)
JSON short full escape 2 x 2,834,774 ops/sec ±1.97% (90 runs sampled)
this short full escape 2 x 3,523,461 ops/sec ±2.18% (91 runs sampled)
JSON short minimal escape x 2,720,557 ops/sec ±2.80% (89 runs sampled)
this short minimal escape x 3,498,311 ops/sec ±2.38% (91 runs sampled)
JSON longer non escape x 2,227,777 ops/sec ±2.88% (87 runs sampled)
this longer non escape x 7,197,187 ops/sec ±1.22% (95 runs sampled)
JSON longer full escape x 2,228,338 ops/sec ±1.06% (91 runs sampled)
this longer full escape x 2,130,231 ops/sec ±2.14% (90 runs sampled)
JSON longer minimal escape x 2,408,445 ops/sec ±3.36% (93 runs sampled)
this longer minimal escape x 2,006,347 ops/sec ±1.89% (90 runs sampled)
The benchmarks ran on Node.js 10.2.1 using a Lenovo T450s with an i7-5600u. The "longer" benchmarks are worst case benchmarks.