我想使用节点js返回文件的内容

Question

I have written the following code in protractor.

helper.js:

var fs = require('fs');
helper = function(){
    this.blnReturn = function(){
        var filePath = '../Protractor_PgObjModel/Results/DontDelete.txt';
        fs.readFileSync(filePath, {encoding: 'utf-8'}, function (err, data){
            if (!err) {
                console.log(data);
                return data;
            } else {
               return "False";
            }
        });
    };
};
module.exports = new helper();

------------actual file where the above js is being called-------------------

describe("read contents of file",function(){
  var helper = require("../GenericUtilities/helper.js");
  it('To Test read data',function(){
    console.log("helper test - " + helper.blnReturn());   
  });
});

-------Output-------------

helper test - undefined

Any help in this regard is much appreciated as it is blocking my work.

Answer 1

you are confusing between reading file synchronously( readFileSync ) and async( readFile ).

you are trying to read the file synchronously, but also using a callback parameter, the right way would be either

return fs.readFileSync(filePath, {encoding: 'utf-8'});

or

this.blnReturn = function(cb){
    ...
    fs.readFileSync(filePath, {encoding: 'utf-8'}, function (err, data){
        if (!err) {
            console.log(data);
            cb(data);
        } else {
           cb("False");
        }
    });

also, on an unrelated note, var keyword is missing in helper definition, the helper.js can be reduced to:

var fs = require('fs');
function helper(){}

helper.prototype.blnReturn = function(){
    var filePath = '../request.js';
    return fs.readFileSync(filePath, {encoding: 'utf-8'});
};

module.exports = new helper();