Javascript 实现 sprintf


Javascript 实现 sprintf

  • 实现

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    str_repeat(i, m) {
    for (var o = []; m > 0; o[--m] = i);
    return o.join('');
    },
    sprintf() {
    var i = 0, a, f = arguments[i++], o = [], m, p, c, x, s = '';
    while (f) {
    if (m = /^[^\x25]+/.exec(f)) {
    o.push(m[0]);
    }
    else if (m = /^\x25{2}/.exec(f)) {
    o.push('%');
    }
    else if (m = /^\x25(?:(\d+)\$)?(\+)?(0|'[^$])?(-)?(\d+)?(?:\.(\d+))?([b-fosuxX])/.exec(f)) {
    if (((a = arguments[m[1] || i++]) == null) || (a == undefined)) {
    throw('Too few arguments.');
    }
    if (/[^s]/.test(m[7]) && (typeof(a) != 'number')) {
    throw('Expecting number but found ' + typeof(a));
    }
    switch (m[7]) {
    case 'b': a = a.toString(2); break;
    case 'c': a = String.fromCharCode(a); break;
    case 'd': a = parseInt(a); break;
    case 'e': a = m[6] ? a.toExponential(m[6]) : a.toExponential(); break;
    case 'f': a = m[6] ? parseFloat(a).toFixed(m[6]) : parseFloat(a); break;
    case 'o': a = a.toString(8); break;
    case 's': a = ((a = String(a)) && m[6] ? a.substring(0, m[6]) : a); break;
    case 'u': a = Math.abs(a); break;
    case 'x': a = a.toString(16); break;
    case 'X': a = a.toString(16).toUpperCase(); break;
    }
    a = (/[def]/.test(m[7]) && m[2] && a >= 0 ? '+'+ a : a);
    c = m[3] ? m[3] == '0' ? '0' : m[3].charAt(1) : ' ';
    x = m[5] - String(a).length - s.length;
    p = m[5] ? this.str_repeat(c, x) : '';
    o.push(s + (m[4] ? a + p : p + a));
    }
    else {
    throw('Huh ?!');
    }
    f = f.substring(m[0].length);
    }
    return o.join('');
    },
  • 使用

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sprintf("%d",this._num);