The map() method creates a new array with the results of calling a function for every array element.The map() method calls the provided function once for each element in an array, in order.Note: map() does not execute the function for array elements without values....
The some() method checks if any of the elements in an array pass a test (provided as a function).The some() method executes the function once for each element present in the array:If it finds an array element where the function returns a true value, some() returns true (and does ...
❮PreviousJavaScript ArrayReferenceNext❯ Example 1 Check if any values are over 18: constages = [3,10,18,20]; ages.some(checkAdult); functioncheckAdult(age) { returnage >18; } Try it Yourself » Description Thesome()method checks if any array elements pass a test (provided as a...
❮PreviousJavaScript ArrayReferenceNext❯ Examples Return a new array with the square root of all element values: constnumbers = [4,9,16,25]; constnewArr = numbers.map(Math.sqrt) Try it Yourself » Multiply all the values in an array with 10: ...
arguments[1] :void0;17for(vari = 0; i < len; i++) {18if(iint) {19varval =t[i];2021//NOTE: Technically this should Object.defineProperty at22//the next index, as push can be affected by23//properties on Object.prototype and Array.prototype.24//But that method's new, and collis...
* 本文纯粹是梳理一下目前W3C标准中Array对象的自带Method。 * 全文没啥营养,不过最后性能测试的部分,倒是抛出了一些疑问。 */ 赋值方法 (Mutator methods) 这些方法直接修改数组自身 pop 和 push Array.pop(); // 删除数组最后一个元素,返回被删除的元素 ...
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The reduceRight() method returns a single value: the function's accumulated result. The reduceRight() method does not execute the function for empty elements. Note At the first callback, there is no return value from the previous callback. Normally, the last array element is used as initial...
Thejoin()method converts all the elements of an array into a new string. letfish=["piranha","barracuda","koi","eel"]; Copy If no argument is given, the output ofjoin()will be a comma-separated string with no extra whitespace. ...
1. Using the push() Method The push() method adds an element at the end of the array. let dailyActivities = ["eat", "sleep"]; // add an element at the end dailyActivities.push("exercise"); console.log(dailyActivities); // Output: [ 'eat', 'sleep', 'exercise' ] Run Code ...