formatting.ts

import * as ts from "typescript";

// Note: this uses ts.formatting which is part of the typescript 1.4 package but is not currently 
//       exposed in the public typescript.d.ts. The typings should be exposed in the next release. 
function format(text: string) {
    let options = getDefaultOptions();

    // Parse the source text
    let sourceFile = ts.createSourceFile("file.ts", text, ts.ScriptTarget.Latest, /*setParentPointers*/ true);

    // Get the formatting edits on the input sources
    let edits = (<any>ts).formatting.formatDocument(sourceFile, getRuleProvider(options), options);

    // Apply the edits on the input code
    return applyEdits(text, edits);

    function getRuleProvider(options: ts.FormatCodeOptions) {
        // Share this between multiple formatters using the same options.
        // This represents the bulk of the space the formatter uses.
        let ruleProvider = new (<any>ts).formatting.RulesProvider();
        ruleProvider.ensureUpToDate(options);
        return ruleProvider;
    }

    function applyEdits(text: string, edits: ts.TextChange[]): string {
        // Apply edits in reverse on the existing text
        let result = text;
        for (let i = edits.length - 1; i >= 0; i--) {
            let change = edits[i];
            let head = result.slice(0, change.span.start);
            let tail = result.slice(change.span.start + change.span.length)
            result = head + change.newText + tail;
        }
        return result;
    }

    function getDefaultOptions(): ts.FormatCodeOptions {
        return {
            IndentSize: 4,
            TabSize: 4,
            NewLineCharacter: '\r\n',
            ConvertTabsToSpaces: true,
            InsertSpaceAfterCommaDelimiter: true,
            InsertSpaceAfterSemicolonInForStatements: true,
            InsertSpaceBeforeAndAfterBinaryOperators: true,
            InsertSpaceAfterKeywordsInControlFlowStatements: true,
            InsertSpaceAfterFunctionKeywordForAnonymousFunctions: false,
            InsertSpaceAfterOpeningAndBeforeClosingNonemptyParenthesis: false,
            InsertSpaceAfterOpeningAndBeforeClosingNonemptyBrackets: true,
            InsertSpaceAfterOpeningAndBeforeClosingTemplateStringBraces: true,
            IndentStyle: ts.IndentStyle.Smart,
            PlaceOpenBraceOnNewLineForFunctions: true,
            PlaceOpenBraceOnNewLineForControlBlocks: false,
        };
    }
}


let code = `
function test():void {
//something
}`;
let result = format(code);
console.log(result);

output.cmd

function test(): void
{
    //something
}