學習筆記 JavaScript Array 數組 方法 函數
<html>
<head>
<script>
var num = [1, 2, 3, 4, 5, 6, 7, 5, 4, 3, 2, 1];
console.log(num.indexOf(4)); // 3
console.log(num.lastIndexOf(3)); // 9
var everyResult = num.every(function(item1, index1, array1) {
return (item1 > 2);
});
console.log(everyResult); //false
var someResult = num.some(function(item, index, array) {
return (item > 2);
});
console.log(someResult); //true
var filterResult = num.filter(function(item, index, array) {
return (item > 2);
});
console.log(filterResult); //[3, 4, 5, 6, 7, 5, 4, 3]
var mapResult = num.map(function(item, index, array) {
return (item + 6);
});
console.log(mapResult); //[7, 8, 9, 10, 11, 12, 13, 11, 10, 9, 8, 7]
num.forEach(function(item, index, array) {
console.log(item); //print num array
});
var reduceResult = num.reduce(function(prev, curr, index, array) {
return (prev + curr);
});
console.log(reduceResult); //43
var reduceRightResult = num.reduceRight(function(prev, curr, index, array) {
return (prev + curr);
});
console.log(reduceRightResult); //43
</script>
</head>
<body>
</body>
</html>