源码
哪些是下标的哪些是个数的?
interface Array<T> {
length: number;
/** 返回,隔开的元素字符串 */
toString(): string;
/** 返回separator隔开的元素字符串*/
join(separator?: string): string;
/** 和toString几乎一致,会根据区域进行额外调整(未深入研究)*/
toLocaleString(): string;
/** 【修改原数组】插入元素或数组到数组末尾,并返回新数组长度*/
push(...items: T[]): number;
/** 【修改原数组】删除最后一个元素并返回 */
pop(): T | undefined;
/** 【修改原数组】删除第一个元素并返回*/
shift(): T | undefined;
/** 【修改原数组】插入元素或数组到数组头，返回新数组长度*/
unshift(...items: T[]): number;
/** 【修改原数组】反转数组并返回原数组的引用*/
reverse(): T[];
/** 【修改原数组】原地排序,返回原数组的索引,默认ASCII排序 */
sort(compareFn?: (a: T, b: T) => number): this;
/** 【修改原数组】移除下标s开始d个元素,并在移除位置插入items,返回移除的元素数组*/
splice(start: number, deleteCount?: number): T[];
splice(start: number, deleteCount: number, ...items: T[]): T[];
/** 连接 一个或多个数组,返回新数组*/
concat(...items: ConcatArray<T>[]): T[];
concat(...items: (T | ConcatArray<T>)[]): T[];
/** slice(s,e)切片,返回[s-e)间的数组段,s为undefined时代表0,e为undefined时代表length-1,s为负数时代表从下标倒数s个数开始
* slice(),=slice(0,length-1),返回原数组的复制
* slice(undefined,1),=slice(0,1)
* slice(1),代表从下标1开始切到最后
* slice(-1),代表从下标倒数第1个数开始切到最后
*/
slice(start?: number, end?: number): T[];
/** 返回查找的元素第一次出现时下标,没找到返回-1,注意 `!!-1 === true`,从第fromIndex个开始找,非下标*/
indexOf(searchElement: T, fromIndex?: number): number;
/** 返回查找的元素最后出现时下标,没找到返回-1*/
lastIndexOf(searchElement: T, fromIndex?: number): number;
/**
* Determines whether all the members of an array satisfy the specified test.
* @param predicate A function that accepts up to three arguments. The every method calls
* the predicate function for each element in the array until the predicate returns a value
* which is coercible to the Boolean value false, or until the end of the array.
* @param thisArg An object to which the this keyword can refer in the predicate function.
* If thisArg is omitted, undefined is used as the this value.
*/
every<S extends T>(predicate: (value: T, index: number, array: T[]) => value is S, thisArg?: any): this is S[];
/**
* Determines whether all the members of an array satisfy the specified test.
* @param predicate A function that accepts up to three arguments. The every method calls
* the predicate function for each element in the array until the predicate returns a value
* which is coercible to the Boolean value false, or until the end of the array.
* @param thisArg An object to which the this keyword can refer in the predicate function.
* If thisArg is omitted, undefined is used as the this value.
*/
every(predicate: (value: T, index: number, array: T[]) => unknown, thisArg?: any): boolean;
/**
* Determines whether the specified callback function returns true for any element of an array.
* @param predicate A function that accepts up to three arguments. The some method calls
* the predicate function for each element in the array until the predicate returns a value
* which is coercible to the Boolean value true, or until the end of the array.
* @param thisArg An object to which the this keyword can refer in the predicate function.
* If thisArg is omitted, undefined is used as the this value.
*/
some(predicate: (value: T, index: number, array: T[]) => unknown, thisArg?: any): boolean;
/**
* Performs the specified action for each element in an array.
* @param callbackfn A function that accepts up to three arguments. forEach calls the callbackfn function one time for each element in the array.
* @param thisArg An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.
*/
forEach(callbackfn: (value: T, index: number, array: T[]) => void, thisArg?: any): void;
/**
* Calls a defined callback function on each element of an array, and returns an array that contains the results.
* @param callbackfn A function that accepts up to three arguments. The map method calls the callbackfn function one time for each element in the array.
* @param thisArg An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.
*/
map<U>(callbackfn: (value: T, index: number, array: T[]) => U, thisArg?: any): U[];
/**
* Returns the elements of an array that meet the condition specified in a callback function.
* @param predicate A function that accepts up to three arguments. The filter method calls the predicate function one time for each element in the array.
* @param thisArg An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.
*/
filter<S extends T>(predicate: (value: T, index: number, array: T[]) => value is S, thisArg?: any): S[];
/**
* Returns the elements of an array that meet the condition specified in a callback function.
* @param predicate A function that accepts up to three arguments. The filter method calls the predicate function one time for each element in the array.
* @param thisArg An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.
*/
filter(predicate: (value: T, index: number, array: T[]) => unknown, thisArg?: any): T[];
/**
* Calls the specified callback function for all the elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
* @param callbackfn A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.
* @param initialValue If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.
*/
reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T;
reduce(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T;
/**
* Calls the specified callback function for all the elements in an array. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
* @param callbackfn A function that accepts up to four arguments. The reduce method calls the callbackfn function one time for each element in the array.
* @param initialValue If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.
*/
reduce<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U;
/**
* Calls the specified callback function for all the elements in an array, in descending order. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
* @param callbackfn A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.
* @param initialValue If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.
*/
reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T): T;
reduceRight(callbackfn: (previousValue: T, currentValue: T, currentIndex: number, array: T[]) => T, initialValue: T): T;
/**
* Calls the specified callback function for all the elements in an array, in descending order. The return value of the callback function is the accumulated result, and is provided as an argument in the next call to the callback function.
* @param callbackfn A function that accepts up to four arguments. The reduceRight method calls the callbackfn function one time for each element in the array.
* @param initialValue If initialValue is specified, it is used as the initial value to start the accumulation. The first call to the callbackfn function provides this value as an argument instead of an array value.
*/
reduceRight<U>(callbackfn: (previousValue: U, currentValue: T, currentIndex: number, array: T[]) => U, initialValue: U): U;
[n: number]: T;
}slice splice
```js
/** slice(s,e)切片,返回[s-e)间的数组段,s为undefined时代表0,e为undefined时代表length-1,s为负数时代表从下标倒数s个数开始
* slice(),=slice(0,length-1),返回原数组的复制
* slice(undefined,1),=slice(0,1)
* slice(1),代表从下标1开始切到最后
* slice(-1),代表从下标倒数第1个数开始切到最后
*/
slice(start?: number, end?: number): T[];
``
