javascript 實現php str_pad

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* 查看php.net官方手冊

string str_pad ( string $input , int $pad_length [, string $pad_string = " " [, int $pad_type = STR_PAD_RIGHT ]] )

 

* javascript code

/** * Pad a string to a certain length with another string */var STR_PAD_LEFT = 1,STR_PAD_RIGHT = 1<<1,STR_PAD_BOTH = STR_PAD_LEFT|STR_PAD_RIGHT;function str_pad(input, pad_length, pad_string, pad_type) {    var input = typeof input === "string" ? input : String.valueOf()(input);    var i, j;    var n = pad_length - input.length;        if (n <= 0)        return input;    var s = pad_string || " ",        offset = s.length,        p = "";  // 要填充的字串(可能會重複);        switch (pad_type) {    case STR_PAD_BOTH:    var q="";        for (i = 0, j=0; 0 < n; n--, i = (i+1) % s.length, j++) {        // 先在右邊添加 後再左邊添加        if (Math.floor(j / s.length) % 2 === 0) {        q += s.charAt(i);                } else {        p += s.charAt(i);        }                }        input = p + input + q;    break;        case STR_PAD_LEFT:        for (i = 0; 0 < n; n--, i = (i+1) % s.length) {        p += s.charAt(i);        }            input = p + input;            break;                case STR_PAD_RIGHT:        default:        for (i = 0; 0 < n; n--, i = (i+1) % s.length) {        p += s.charAt(i);        }            input = input + p;    }    return input;}

　　

* test

// testfunction echo(s) {console.log("\"" +s + "\"");}var $input = "Alien";echo (str_pad($input, 10));                      // produces "Alien     "echo (str_pad($input, 10, "-=", STR_PAD_LEFT));  // produces "-=-=-Alien"echo (str_pad($input, 10, "_", STR_PAD_BOTH));   // produces "__Alien___"echo (str_pad($input,  6, "___"));               // produces "Alien_"echo (str_pad($input,  3, "*"));                 // produces "Alien" /*function substr(s, begin, end) {var ns = "", end = end || s.length;for (var i = begin; i < end; i++) {ns += s.charAt(i);}return ns;}*/

　　

* Run:

 

javascript 實現php str_pad