CODEWITHSUNDEEP
javascriptcallbackargumentspromise
user4209821
user4209821

Reputation:

Send promise with two params

How to pass an additional parameter to handleFile? 

return fs.readFileAsync(path, 'utf8')
    .then(handleFile)
    .then(Process)
    // ...

var handleFile = function (data) {
    var keyVal = {};
    data.split("\n").forEach(function (element) {

// ...

I handle vfile get data from the readFileAsync.

I need it to be something like (pseudo code):

return fs.readFileAsync(path, 'utf8')
                .then(handleFile(newParam1,newParam2))
                .then(Process)

                // ...


var handleFile = function (data,newParam1,newParam2) {

Upvotes: 3

Views: 92

Answers (2)

krl
krl

Reputation: 5296

return fs.readFileAsync(path, 'utf8')
         .then(function(data) { 
            // get newParam1, newParam2 here or make sure they are available in closure
            return handleFile(data, newParam1, newParam2); 
         })
         .then(Process)
         ....


var handleFile = function (data,newParam1,newParam2) {

Upvotes: 0

tomastrajan
tomastrajan

Reputation: 1726

You can use .bind() for it. It is a way to do partial application and set the execution scope (which shouldn't be important in your case hence null)

.then(handleFile.bind(null, newParam1,newParam2))

var handleFile = function (newParam1,newParam2, data,) { // ...

You can also implement yourself partial application without use of bind, then it will look like:

function handleFileWithParams(param1, param2) {
    return function handleFile(data) {
        // ... do stuff
    } 
}

.then(handleFileWithParams(param1, param2))

Lastly when you are already using library like lodash, you can use provided function _.partial which does exactly that.

Upvotes: 1

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