for循環:

復制代碼 代碼如下:

for(i=start; i<end; i++) {

}

復制代碼 代碼如下:

while (condition) {
//do something;
//change condition;
}

復制代碼 代碼如下:

function substring(all, start, end) {
for(i=start; i<=end; i++) {
console.log(all[i]);
}

substring("eclipse", 1, 4); //clip

復制代碼 代碼如下:

function substring(all, start, end) {
if(start >= end) {
return all[start];
}
else {
return all[start] + substring(all, start+1, end);
}

substring("eclipse", 1, 4); //clip

對于數組,字符串, 我們使用index []訪問特定的值; 對于對象,也是一樣使用[], 但我們會使用一個特殊的變量: propertyName

復制代碼 代碼如下:

var person = {
name: "Morgan Jones",
telephone: "(650) 777 - 7777",
email: "morgan.jones@example.com"
};

for (var propertyName in person) {
console.log(propertyName + ":"+ person[propertyName]);
}

復制代碼 代碼如下:

var table = [
["Person", "Age", "City"],
["Sue",22,"San Francisco"],
["Joe",45,"Halifax"]
];

var i;
var rows=table.length;
for (r=0;r<rows;r++) {
var c;
var cells = table[r].length;
var rowText = "";
for (c=0;c<cells;c++) {
rowText += table[r][c];
if (c < cells-1) {
rowText += " ";
}
}
console.log(rowText);
}

Sue 22 San Francisco

Joe 45 Halifax

--------------------------------------------------------------------------------

break:

使用break立刻退出循環, 適用于for和while循環.