Javascript map return multiple values

Recorrer array de objetos javascript

Acciones del artículoEsta página ha sido traducida del inglés por la comunidad. Aprende más y únete a la comunidad MDN Web Docs.Object.entries()El método Object.entries() devuelve una matriz de pares propios de una propiedad enumerable [key, value] de un objeto dado, en el mismo orden que es proporcionado por for…in (La diferencia es que un bucle for-in enumera las propiedades en la cadena de prototipos).SintaxisObject.entries(obj)

Valor de retornoUn array de pares de propiedades enumerables [clave, valor] propias del objeto dado.DescripciónObjeto.entries() devuelve un array cuyos elementos son matrices correspondientes a los pares de propiedades enumerables [clave, valor] que se encuentran directamente en el objeto. El orden de las propiedades es el mismo que el que se da al recorrer los valores de las propiedades del objeto manualmente.Ejemplosvar obj = { foo: ‘bar’, baz: 42 };

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In the second loop, the variable i was declared using the reserved word let: variables declared with the reserved word let (and const) have a block scope (a block is what is between {}). During each iteration, i will have a new value, and each value is inside the loop.

With arrow functions, the this keyword refers to their current scope, unlike regular functions. This means that when we call “perimeter”, it does not refer to the object itself, but to its surrounding scope (window for example).

What JS does here is register the object because we just created an empty object in the global object. When we mistakenly write greeting as greetign, the JS interpreter sees this as global.greetign = {} (or window.greetign = {} in a browser).

Javascript map array of objects

When you run this code, you will be warned that a key should be provided for list items. A “key” is a special string attribute that you must include when creating lists of items. We will discuss why this is important in the next section.

Keys help React identify which items have changed, are added, or are deleted. Keys must be given to the elements within the array to give the elements a stable identity:

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We do not recommend using indexes for keys if the order of items can change. This can negatively impact performance and can cause problems with component state. Check Robin Pokorny’s article for an in-depth explanation of the negative impacts of using an index as a key. If you choose not to assign an explicit key to the list of items, React will by default use indexes as keys.

The keys serve as a hint to React but are not passed to your components. If you need to use the same value in your component, pass it explicitly as a property with a different name:

Array to map javascript

Statistical Data and Metadata eXchange (SDMX) was created in 2001 by seven organizations working in statistics at the international level: Bank for International Settlements (BIS), European Central Bank (ECB), Eurostat, International Monetary Fund (IMF), Organisation for Economic Co-operation and Development (OECD), United Nations Statistics Division and the World Bank. These seven organizations serve as sponsors of SDMX.

The objective of SDMX was to develop and use more efficient processes for the exchange of statistical data and metadata between international organizations and their member countries. To achieve this goal, standard formats for data and metadata are provided, along with guidelines for content and an IT architecture for the exchange of data and metadata.See more…

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The SDMX initiative establishes standards to facilitate the exchange of statistical data and metadata using modern information technology. Several versions of the technical specifications have been released since 2004. Therefore, it is important to learn about them.more…

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