WebJul 11, 2024 · The following is wrong: function saveFriend () { const newData = [...data, newFriend]; setData (newData); } function saveFriend () { setData ( [...data, newFriend]); } The reason why this doesn't work is, Array.push () returns the length of the array, thereby, setting the data to a number. And an integer doesn't have the map () function so you ... WebDec 23, 2024 · You only need to use the Body.json () method if you are trying to resolve the promise from a Response stream. You may read more about it on the documentation. One use case of doing so would be when you are making a HTTP request using the fetch API, whereby you will have to call Body.json () to return the response body.
Uncaught (in promise) TypeError: res.map is not a function
WebMake sure your response is a list. If you are not sure, what kind of response you are getting, you can log it or inspect it. In the above problem description, you are using axios to fetch the API data and to get the data from the API you need to change it as. setData(res.data) WebNov 13, 2024 · An optional reviver function can be provided to perform a transformation on the resulting object before it is returned. data = JSON.parse (data); Demo: var data = JSON.stringify ( [ {"model": "app.mdl", "pk": 1, "fields": {"name": "test", "rank": 1}}]); data = JSON.parse (data); data.forEach (function (element) { console.log (element); }); crystals are fine grained
TypeError: "x" is not a function - JavaScript MDN - Mozilla
WebJun 12, 2015 · In some cases (not in all), the SIMPLEST answer is to put "data" into a pair of square brackets (i.e. [data]) to change the items in the "data" into an array: $.getJSON ("json/products.json").done (function (data) { var allProducts = [data].map (function (item) { return new getData (item); }); }); WebMay 9, 2015 · The .map function is only available on array. It looks like data isn't in the format you are expecting it to be (it is {} but you are expecting []). this.setState ( {data: data}); should be this.setState ( {data: data.conversations}); Check what type "data" is being set to, and make sure that it is an array. WebMay 22, 2024 · In Example 1, the getTaxAmount(price, taxRate) function, when called, should have returned a Promise that resolves to a value of 12. Currently this function simply calculates the tax amount using the two inputs and does not return a value. Hence, the undefined value is returned. dying together