JavaScript 数组练习题之实现

function filterAdult (arr) {
    var res = [];
    if(Array.isArray(arr)){
        if(arr.filter){// 如果浏览器支持filter
            res = arr.filter(function (each) {
                return each.age > 18;
            })
        } else {
            arr.forEach(function  (each) {
                if(each.age > 18){
                    res.push(each);
                }
            });
        }
    }
    return res;
}

function isAllNumPosive (arr) {
    var res = true;
    if(Array.isArray(arr)){
        if(arr.every){
            res = arr.every(function (each) {
                var isPosive = true;
                if(typeof each === 'number' && each < 0){
                    isPosive = false;
                }
                return isPosive;
            });
        } else {
            arr.forEach(function  (each) {
                if(typeof each === 'number' && each < 0){
                    res = false;
                }
            });
        }
    } else {
        throw new TypeError('param is not Array');
    }
    return res;

}

function putFirst (arr, n) {
    if(Array.isArray(arr)){
        var item = arr.splice(n, 1)[0];
        arr.unshift(item);
    }
}

function toArray (arrLikeObj) {
    return [].slice.call(arrLikeObj);
}

function sum (arr) {
    var res = 0;
    if(Array.isArray(arr)){
        if(arr.reduce){
            res = arr.reduce(function (prev, curr) {
                if(typeof curr === 'number'){
                    return prev + curr;
                }
                return prev;
            }, 0)
        } else {
            arr.forEach(function  (each) {
                if(typeof each === 'number'){
                    res = res + each;
                }
            });
        }
    }
    return res;
}

function sortAge (arr) {
    var res = false;
    if(Array.isArray(arr)){
        res = arr.sort(function (a, b) {
            return a.age < b.age ? -1: 1;
        });
    } else {
        throw new TypeError('param is not Array');
    }
    return res;
}

function uniq (arr) {
    var res = [];
    if(Array.isArray(arr) ){
        arr.forEach(function  (each) {
            if(res.indexOf(each) === -1){
                res.push(each);
            }
        })
    } else {
        throw new TypeError('param is not Array');
    }
    return res;
}
// 或
function uniq (arr) {
    var res = [];
    var cache = {};
    if(Array.isArray(arr) ){
        arr.forEach(function  (each) {
            if(cache[each] === undefined){
                res.push(each);
                cache[each] = true;
            }
        })
    } else {
        throw new TypeError('param is not Array');
    }
    return res;
}

function random(arr) {
    var res;
    if (Array.isArray(arr)) {
        res = arr.sort(function() {
            return Math.random() > 0.5 ? 1 : -1;
        })
    } else {
        throw new TypeError('param is not Array');
    }
    return res;
}