How can we get the Syntax Tree of TypeScript?

The TypeScript compiler API is really quite easy to use. To parse a typescript file and obtain the AST, try the following:

const ts = require('typescript');const sourceFile = ts.createSourceFile(filename,    fs.readFileSync(filename).toString(), ts.ScriptTarget.ES6, false);console.log(sourceFile.ast);

This generates the AST, for example:

{  "kind": 251,  "pos": 0,  "end": 1097,  "flags": 0,  "bindDiagnostics": [],  "languageVersion": 2,  "fileName": "slidingWindow.ts",  "languageVariant": 0,  "scriptKind": 3,  "referencedFiles": [],  "amdDependencies": [],  "statements": [    {      "kind": 218,      "pos": 0,      "end": 69,      "flags": 0,      "name": {        "kind": 69,        "pos": 10,        "end": 22,        "flags": 0,        "text": "Accumulator",        "kindDecoded": "Identifier"      },      "members": [        {          "kind": 148,          "pos": 24,          "end": 67,          "flags": 0,          "parameters": [            {              "kind": 139,              "pos": 28,              "end": 42,              "flags": 0,              "name": {                "kind": 69,                "pos": 28,                "end": 32,                "flags": 0,                "text": "data",                "kindDecoded": "Identifier"              },              "type": {                "kind": 157,                "pos": 33,                "end": 42,                "flags": 0,                "elementType": {                  "kind": 128,                  "pos": 33,                  "end": 40,                  "flags": 0,                  "kindDecoded": "NumberKeyword"                },                "kindDecoded": "ArrayType"              },              "kindDecoded": "Parameter"            },            {              "kind": 139,              "pos": 43,              "end": 57,              "flags": 0,              "name": {                "kind": 69,                "pos": 43,                "end": 49,                "flags": 0,                "text": "index",                "kindDecoded": "Identifier"              },              "type": {                "kind": 128,                "pos": 50,                "end": 57,                "flags": 0,                "kindDecoded": "NumberKeyword"              },              "kindDecoded": "Parameter"            }          ],          "type": {            "kind": 128,            "pos": 59,            "end": 66,            "flags": 0,            "kindDecoded": "NumberKeyword"          },          "kindDecoded": "CallSignature"        }      ],      "kindDecoded": "InterfaceDeclaration"    },...

Do you need to get the AST from a specific compiler or just get the syntax tree from a program in TypeScript? If you are interested in the later, then what you may need to do is grab a BNF grammar for TypeScript (starting point here) and then use ANTLR for example. It has a tool named ANTLRWorks that allows you to visualise the syntax tree of a program.