add setCurrent function and a simple demonstration file

examples/setCurrent.js

@@ -0,0 +1,10 @@
+/**
+ * An example to show a progress bar using setCurrent methdod.
+ */
+
+var ProgressBar = require('../');
+
+var bar = new ProgressBar(':bar :current/:total', {total: 10});
+var timer = setInterval(function () {
+    bar.setCurrent(Math.ceil(Math.random() * bar.total), false);
+}, 200);

lib/node-progress.js

@@ -106,6 +106,52 @@ ProgressBar.prototype.tick = function(len, tokens){
   }
 };
 
+/**
+ * set the progress bar value with 'current' and optional `tokens`.
+ * it is like the tick() method but with two differences:
+ *  - you directly set the value of the curr
+ *  - you can also choose not to finish the progressBar when it reaches the end by param end_at_total
+ * @param {number} current
+ * @param {object} tokens
+ * @param {boolean} end_at_total
+ * @api public
+ */
+
+ProgressBar.prototype.setCurrent = function(current, tokens, end_at_total = true){
+  if (current !== 0)
+    current = current || 1;
+
+  if ('boolean' == typeof tokens) end_at_total = tokens;
+  if ('boolean' == typeof current) current = 1, tokens = {}, end_at_total = current;
+
+  // swap tokens
+  if ('object' == typeof current) tokens = current, current = 1;
+  if (tokens) this.tokens = tokens;
+
+  // start time for eta
+  if (this.start === undefined) this.start = new Date;
+
+  if (current && current < 0) {
+    current = 0;
+  }
+  if (this.total && current > this.total){
+    current = this.total;
+  }
+  this.curr = current;
+
+  // try to render
+  this.render();
+
+  // progress complete
+  if (end_at_total && this.curr >= this.total) {
+    this.render(undefined, true);
+    this.complete = true;
+    this.terminate();
+    this.callback(this);
+    return;
+  }
+};
+
 /**
  * Method to render the progress bar with optional `tokens` to place in the
  * progress bar's `fmt` field.
@@ -139,13 +185,13 @@ ProgressBar.prototype.render = function (tokens, force) {
 
   /* populate the bar template with percentages and timestamps */
   var str = this.fmt
-    .replace(':current', this.curr)
-    .replace(':total', this.total)
-    .replace(':elapsed', isNaN(elapsed) ? '0.0' : (elapsed / 1000).toFixed(1))
-    .replace(':eta', (isNaN(eta) || !isFinite(eta)) ? '0.0' : (eta / 1000)
-      .toFixed(1))
-    .replace(':percent', percent.toFixed(0) + '%')
-    .replace(':rate', Math.round(rate));
+      .replace(':current', this.curr)
+      .replace(':total', this.total)
+      .replace(':elapsed', isNaN(elapsed) ? '0.0' : (elapsed / 1000).toFixed(1))
+      .replace(':eta', (isNaN(eta) || !isFinite(eta)) ? '0.0' : (eta / 1000)
+          .toFixed(1))
+      .replace(':percent', percent.toFixed(0) + '%')
+      .replace(':rate', Math.round(rate));
 
   /* compute the available space (non-zero) for the bar */
   var availableSpace = Math.max(0, this.stream.columns - str.replace(':bar', '').length);