istanbuljs example of programmatic instrumentation, and coverage report.

istanbuljs-api-example-1.js

// In this example we are instrumenting JavaScript code string, executing it, and then generating a coverage report. 

// instrument the code

var instrumenter = require('istanbul-lib-instrument').createInstrumenter({})

var instrumentedCode = instrumenter.instrumentSync('var a = 1; function f(){return 1}; f(); ', 'file1.js')



// execute the code

eval(instrumentedCode)

// at this point the global variable __coverage__ contains the coverage data 

var globalCoverageVar = __coverage__;



// generate the coverage report

var libCoverage = require('istanbul-lib-coverage');
var map = libCoverage.createCoverageMap(globalCoverageVar);

const createReporter = require('istanbul-api').createReporter;

const reporter = createReporter();

reporter.addAll(['json', 'lcov', 'text', 'html']);

reporter.write(map);