四、indexOf()方法: 功能:返回指定元素首次出现的索引,无匹配时返回-1。 const colors = ['red', 'blue', 'green', 'blue']; const blueIndex = colors.indexOf('blue'); console.log(blueIndex); //结果:1,因为blue在数组colors中第一次出现的索引是1。 1. 2. 3. 4. 参数: searchElement:待查...
varages=[2,4,6,8,10];functioncheckAdult(age){returnage>=document.getElementById("ageToCheck").value;}functionmyFunction(){document.getElementById("demo").innerHTML=ages.findIndex(checkAdult);} 注意: findIndex() 对于空数组,函数是不会执行的。 findIndex() 并没有改变数组的原始值。 发布者:...
forEach(function(element,index){ console.log(element + '/' + index); }) //输出结果: first/0 second/1 third/2 fourth/3 3/4 5/5 8/6 5.map 遍历数组,并通过callback对数组元素进行操作,并将所有操作结果放入数组中并返回该数组(不能遍历伪数组) var arr = ["first","second",'third' ...
This method returns the index of the first matched element in the array that satisfies a provided condition. It works similarly to thefind()method, but instead of returning the first matched element, it returns the index of the first matched element. If no matches are found, then it returns ...
代码语言:javascript 复制 functionisBigEnough(element){returnelement>=15;}[12,5,8,130,44].findIndex(isBigEnough);// index of 4th element in the Array is returned,// so this will result in '3' 另请参见find()方法,它返回数组中找到的元素的值,而不是其索引。
Return Value: Returns the array element index if any of the elements in the array pass the test, otherwise it returns undefined JavaScript Version: ECMAScript 6More ExamplesExample Get the index of the first element in the array that has a value above a specific number: Minimum age: Try ...
Vue Js lastindexOf Method : The last index (position) of a given value is returned by the lastIndexOf() method. The search defaults to beginning at the last element and ending at the first. Negative start values begin counting with the previous
In this tutorial, you will learn about the JavaScript Array findIndex() method with the help of examples. The findIndex() method returns the index of the first array element that satisfies the provided test function or else returns -1.
arr.some(callback(element[, index[, array]])[, thisArg]) 返回值: 数组中有至少一个元素通过回调函数的测试就会返回true;所有元素都没有通过回调函数的测试返回值才会为false。 some() 为数组中的每一个元素执行一次 callback 函数,直到找到一个使得 callback 返回一个“真值”(即可转换为布尔值 true 的值...
❮PreviousJavaScript ArrayReferenceNext❯ Example 1 Find the first element with a value over 18: constages = [3,10,18,20]; ages.findIndex(checkAge); functioncheckAge(age) { returnage >18; } Try it Yourself » Description ThefindIndex()method executes a function for each array element...