fix(Stepper): can't work when step is decimal (#2142)

packages/stepper/index.ts

@@ -5,6 +5,12 @@ import { addUnit, isDef } from '../common/utils';
 const LONG_PRESS_START_TIME = 600;
 const LONG_PRESS_INTERVAL = 200;
 
+// add num and avoid float number
+function add(num1: number, num2: number): number {
+  const cardinal = 10 ** 10;
+  return Math.round((num1 + num2) * cardinal) / cardinal;
+}
+
 VantComponent({
   field: true,
 
@@ -18,7 +24,10 @@ VantComponent({
     buttonSize: null,
     asyncChange: Boolean,
     disableInput: Boolean,
-    decimalLength: Number,
+    decimalLength: {
+      type: Number,
+      value: null
+    },
     min: {
       type: null,
       value: 1
@@ -128,12 +137,7 @@ VantComponent({
       }
 
       const diff = type === 'minus' ? -this.data.step : +this.data.step;
-
-      let value = +this.data.value + diff;
-
-      if (!isDef(this.data.decimalLength)) {
-        value = Math.round(value * 100) / 100;
-      }
+      const value = add(+this.data.value, diff);
 
       this.triggerInput(this.range(value));
       this.$emit(type);