Javascript多位數字索引

Question

我在網上搜索過，解決方案一定很簡單，沒人問過嗎？ 我只是想用+ i +這樣的索引來返回001,002,003等

Answer 1

如何

('000' + i).substr(-3); 

Answer 2

所以像這樣？

function number_pad(num,len) { 
    num = ""+num; 
    while(num.length < len) num = "0"+num; 
    return num; 
} 
// Usage: number_pad(i,3); 

可替代地，延伸的原生對象：

Number.prototype.pad(len) { 
    var num = ""+this; 
    while(num.length < len) num = "0"+num; 
    return num; 
} 
// Usage: i.pad(3); 

供將來參考，這被稱爲ZEROFILL或零填充。

Answer 3

function paddedNumber(n) { 
    // A string containing the fully padded zero value. 
    var zeroes = "000"; 
    // The number as a string. 
    var numstr = "" + n; 
    var nDigits = numstr.length; 
    // Keep any sign at the front. 
    var sign = ""; 
    if (/^[\+\-]/.test(numstr)) { 
    sign = numstr.charAt(0); 
    numstr = numstr.substring(1); 
    } 
    // Concatenates the number with just enough zeroes. 
    // No padding if itoa is already longer than the pad. 
    return sign + zeroes.substring(nDigits) + numstr; 
}