CODEWITHSUNDEEP
javascriptpromiseecmascript-6es6-promise
Elliot
Elliot

Reputation: 1983

Simple ES6 promises issue - Swapped resolve and reject parameters

Here I'd expect to see 4 and then 5 in the console. I thought that once the first add resolves, the then would go through the anonymous function, which returns another add.

So what am I missing that causes only the first add to be ran?

Fiddle: http://www.es6fiddle.net/iobmmhs3/

var add =  function(a, b) {
    return new Promise(function(reject, resolve) {
        console.log(a+b);
        resolve(a+b);
    });
};

add(1,3)
.then(function() {
    return add(2,3)
})

Upvotes: 0

Views: 54

Answers (1)

xdumaine
xdumaine

Reputation: 10329

Your resolve and reject are backwards:

var add =  function(a, b) {
    return new Promise(function(resolve, reject) {
        //                      ^^^^^^^  ^^^^^^
        console.log(a+b);
        resolve(a+b);
    });
};

add(1,5)
.then(function() {
    return add(2,2)
});

Fiddle: http://www.es6fiddle.net/iobm7rb7/

For documentation, see MDN. For future reference, how you could have debugged this without knowing the signature of the function passed to the constructor: in the console, you should have seen an Uncaught in Promise error, which is indicating that your promise rejected, and didn't have a reject handler.

Upvotes: 4

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