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How to cut off individual items in a javascript list

Entrance: dates = [201701, 201702, 201703]

I need output as [2017-01, 2017-02, 2017-03]

I tried using slice method in javascript but it fails

for (var i in dates) {
dates[i].slice(0, 4) + "-" + dates[i].slice(4);
}

It fails.

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2 answers


You just forgot toString()

:



var dates =  [201701, 201702, 201703];

for (var i = 0; i < dates.length; i++) {
  console.log(dates[i].toString().slice(0, 4) + "-" + dates[i].toString().slice(4));
}
Run code


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You can use Number#toString

it String#replace

for the dates you want.



var dates =  [201701, 201702, 201703],
    result = dates.map(a => a.toString().replace(/(?=..$)/, '-'));
    
console.log(result);
Run code


Or use String#split

.



var dates =  [201701, 201702, 201703],
    result = dates.map(a => a.toString().split(/(?=..$)/).join('-'));
    
console.log(result);
Run code


Both ES5 examples



var dates =  [201701, 201702, 201703];

console.log(dates.map(function (a) { return a.toString().replace(/(?=..$)/, '-'); }));
console.log(dates.map(function (a) { return a.toString().split(/(?=..$)/).join('-'); }));
Run code


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