SOURCE

 var arrlist = []

 
 for (let i = 1; i < 301; i++) {
      var obj =  {
            "schemaCode":"${schemaCode}",
            "variantCode":"12PIM-PEM${variantCode}",
            "properties":{
                "customSize":"26",
                "skuTagPrice":1212,
                "customColor":{
                                "customColorID":"purple",
                    "customColorName":"purple"
                    
                },
                "basecolor":"purple",
                "barcode":"",
                "barcodeList":"",
                "saleLocation":"",
                "customSizeDesc":"",
                "skuCode":"",
                "brandSkuCode":"12${brandSkuCode}",
                "platformCode":"12PIM-PEM${variantCode}",
                "grossWeight":"",
                "netWeight":"",
                "americaSize":"",
                "EuroSize":"",
                "engSize":"",
                "generalsize":""
            }
        }

        obj.variantCode = i+30+"PIM-PEM${variantCode}"
        obj.properties.platformCode = i+30+"PIM-PEM${variantCode}"
        obj.properties.skuTagPrice = 1230 + i
        obj.properties.brandSkuCode = i+30+"${brandSkuCode}"
        obj.properties.customSize = i +"XL"

        arrlist.push(obj)
    }

console.log(arrlist)