ES5的数组方法

[1, 2, 3, 4, 5].forEach(function(item, index, array) {  
    console.log(‘the current index is: ‘ + index + ‘, value is: ‘ + item);  
});  

var oddArr = [1, 2, 3, 4, 5].filter(function(item) {  
    return item % 2 !== 0;  
});

var arr = [1,1,2,3,5,5,2,9,0,0].filter((item,index,arr)=>{
    return arr.indexOf(item) === index;
});

var arr = [...new Set([1,1,2,3,5,5,2,9,0,0])];

var doubleArr = [1, 2, 3, 4, 5].map(function(item) {  
    return item * 2;  
});

var someoneGreaterThan3 = [1, 2, 3, 4, 5].some(function(item) {  
    return item > 3;  
});