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Array Functions are the gateway to functional programming in JavaScript. These functions make short work of most imperative programming routines that work on arrays and collections.
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***[].every(fn)***
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Checks if all elements in an array pass a test.
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***[].some(fn) | [].includes(fn)***
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Checks if any of the elements in an array pass a test.
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***[].find(fn)***
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Returns the value of the first element in the array that passes a test.
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***[].filter(fn)***
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Creates an array filled with only the array elements that pass a test.
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***[].map(fn)***
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Creates a new array with the results of a function applied to every element in the array.
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***[].reduce(fn(accumulator, currentValue))***
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Executes a provided function for each value of the array (from left-to-right). Returns a single value, the accumulator.
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***[].sort(fn(a,b))*** warning, mutates state!
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Modifies an array by sorting the items within an array. An optional compare function can be used to customize sort behavior. Use the spread operator to avoid mutation. [...arr].sort()
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***[].reverse()*** warning, mutates state!
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Reverses the order of the elements in an array. Use the spread operator to avoid mutation. [...arr] . reverse()
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For example:
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```javascript
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constnames= [
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{text:"Alpha", value:5},
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{text:"Beta", value:2},
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{text:"Gamma", value:4},
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];
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//Checks if all elements in an array pass a test.
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let everyResult =names.every(x=>x.value>0); //true
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// Checks if any of the elements in an array pass a test.
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let someResult =names.some(x=>x.text==="Alpha"); //true
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// Returns the value of the first element in the array that passes a test.
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let findResult =names.find(x=>x.text==="Gamma"); //{text: "Gamma", value: 4}
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// Creates an array filled with only the array elements that pass a test.
// Executes a provided function for each value of the array (from left-to-right). The returns a single value, the accumulator.
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let reduceResult =names.reduce((accumulator, currentValue) =>currentValue.value>accumulator.value? currentValue : accumulator);
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// Get the largest object by value: {"text":"Alpha","value":5}
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// Modifies an array by sorting the items within an array. An optional compare function can be used to customize sort behavior. Use the spread operator to avoid mutation. [...arr].sort()
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let sortResult = [...names].sort((a,b) =>b.value-a.value);
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// reverses the order of the elements in an array. Use the spread operator to avoid mutation. [...arr].reverse()
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