Function d3_interpolateString

d3-3.2.8/d3.js:4980–5044

(a, b)

  }
  d3.interpolateString = d3_interpolateString;
  function d3_interpolateString(a, b) {
    var m, i, j, s0 = 0, s1 = 0, s = [], q = [], n, o;
    a = a + "", b = b + "";
    d3_interpolate_number.lastIndex = 0;
    for (i = 0; m = d3_interpolate_number.exec(b); ++i) {
      if (m.index) s.push(b.substring(s0, s1 = m.index));
      q.push({
        i: s.length,
        x: m[0]
      });
      s.push(null);
      s0 = d3_interpolate_number.lastIndex;
    }
    if (s0 < b.length) s.push(b.substring(s0));
    for (i = 0, n = q.length; (m = d3_interpolate_number.exec(a)) && i < n; ++i) {
      o = q[i];
      if (o.x == m[0]) {
        if (o.i) {
          if (s[o.i + 1] == null) {
            s[o.i - 1] += o.x;
            s.splice(o.i, 1);
            for (j = i + 1; j < n; ++j) q[j].i--;
          } else {
            s[o.i - 1] += o.x + s[o.i + 1];
            s.splice(o.i, 2);
            for (j = i + 1; j < n; ++j) q[j].i -= 2;
          }
        } else {
          if (s[o.i + 1] == null) {
            s[o.i] = o.x;
          } else {
            s[o.i] = o.x + s[o.i + 1];
            s.splice(o.i + 1, 1);
            for (j = i + 1; j < n; ++j) q[j].i--;
          }
        }
        q.splice(i, 1);
        n--;
        i--;
      } else {
        o.x = d3_interpolateNumber(parseFloat(m[0]), parseFloat(o.x));
      }
    }
    while (i < n) {
      o = q.pop();
      if (s[o.i + 1] == null) {
        s[o.i] = o.x;
      } else {
        s[o.i] = o.x + s[o.i + 1];
        s.splice(o.i + 1, 1);
      }
      n--;
    }
    if (s.length === 1) {
      return s[0] == null ? (o = q[0].x, function(t) {
        return o(t) + "";
      }) : function() {
        return b;